1 /*
2 * Copyright (c) 1997, 2013, 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).
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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 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 // Threshold for performing small range operation, even when large range
60 // operation was requested. Measured in words.
61 static const size_t small_range_words = 32;
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() const { return _map; }
80 bm_word_t map(idx_t word) const { return _map[word]; }
81
82 // Return a pointer to the word containing the specified bit.
83 bm_word_t* word_addr(idx_t bit) const { return map() + word_index(bit); }
84
85 // Set a word to a specified value or to all ones; clear a word.
86 void set_word (idx_t word, bm_word_t val) { _map[word] = val; }
87 void set_word (idx_t word) { set_word(word, ~(uintptr_t)0); }
88 void clear_word(idx_t word) { _map[word] = 0; }
89
90 // Utilities for ranges of bits. Ranges are half-open [beg, end).
91
92 // Ranges within a single word.
93 bm_word_t inverted_bit_mask_for_range(idx_t beg, idx_t end) const;
94 void set_range_within_word (idx_t beg, idx_t end);
95 void clear_range_within_word (idx_t beg, idx_t end);
96 void par_put_range_within_word (idx_t beg, idx_t end, bool value);
97
98 // Ranges spanning entire words.
99 void set_range_of_words (idx_t beg, idx_t end);
100 void clear_range_of_words (idx_t beg, idx_t end);
101 void set_large_range_of_words (idx_t beg, idx_t end);
102 void clear_large_range_of_words (idx_t beg, idx_t end);
103
104 static bool is_small_range_of_words(idx_t beg_full_word, idx_t end_full_word);
105
106 // The index of the first full word in a range.
107 idx_t word_index_round_up(idx_t bit) const;
108
109 // Verification.
110 inline void verify_index(idx_t index) const NOT_DEBUG_RETURN;
111 inline void verify_range(idx_t beg_index, idx_t end_index) const
112 NOT_DEBUG_RETURN;
113
114 // Statistics.
115 static idx_t* _pop_count_table;
116 static void init_pop_count_table();
117 static idx_t num_set_bits(bm_word_t w);
118 static idx_t num_set_bits_from_table(unsigned char c);
119
120 public:
121
122 // Constructs a bitmap with no map, and size 0.
123 BitMap() : _map(NULL), _size(0), _map_allocator(false) {}
124
125 // Constructs a bitmap with the given map and size.
126 BitMap(bm_word_t* map, idx_t size_in_bits);
127
128 // Constructs an empty bitmap of the given size (that is, this clears the
129 // new bitmap). Allocates the map array in resource area if
130 // "in_resource_area" is true, else in the C heap.
131 BitMap(idx_t size_in_bits, bool in_resource_area = true);
132
133 // Set the map and size.
134 void set_map(bm_word_t* map) { _map = map; }
135 void set_size(idx_t size_in_bits) { _size = size_in_bits; }
136
137 // Allocates necessary data structure, either in the resource area
138 // or in the C heap, as indicated by "in_resource_area."
139 // Preserves state currently in bit map by copying data.
140 // Zeros any newly-addressable bits.
141 // If "in_resource_area" is false, frees the current map.
142 // (Note that this assumes that all calls to "resize" on the same BitMap
143 // use the same value for "in_resource_area".)
144 void resize(idx_t size_in_bits, bool in_resource_area = true);
145
146 // Accessing
147 idx_t size() const { return _size; }
148 idx_t size_in_words() const {
149 return word_index(size() + BitsPerWord - 1);
150 }
151
152 bool at(idx_t index) const {
153 verify_index(index);
154 return (*word_addr(index) & bit_mask(index)) != 0;
155 }
156
157 // Align bit index up or down to the next bitmap word boundary, or check
158 // alignment.
159 static idx_t word_align_up(idx_t bit) {
160 return align_size_up(bit, BitsPerWord);
161 }
162 static idx_t word_align_down(idx_t bit) {
163 return align_size_down(bit, BitsPerWord);
164 }
165 static bool is_word_aligned(idx_t bit) {
166 return word_align_up(bit) == bit;
167 }
168
169 // Set or clear the specified bit.
170 inline void set_bit(idx_t bit);
171 inline void clear_bit(idx_t bit);
172
173 // Atomically set or clear the specified bit.
174 inline bool par_set_bit(idx_t bit);
175 inline bool par_clear_bit(idx_t bit);
176
177 // Put the given value at the given offset. The parallel version
178 // will CAS the value into the bitmap and is quite a bit slower.
179 // The parallel version also returns a value indicating if the
180 // calling thread was the one that changed the value of the bit.
181 void at_put(idx_t index, bool value);
182 bool par_at_put(idx_t index, bool value);
183
184 // Update a range of bits. Ranges are half-open [beg, end).
185 void set_range (idx_t beg, idx_t end);
186 void clear_range (idx_t beg, idx_t end);
187 void set_large_range (idx_t beg, idx_t end);
188 void clear_large_range (idx_t beg, idx_t end);
189 void at_put_range(idx_t beg, idx_t end, bool value);
190 void par_at_put_range(idx_t beg, idx_t end, bool value);
191 void at_put_large_range(idx_t beg, idx_t end, bool value);
192 void par_at_put_large_range(idx_t beg, idx_t end, bool value);
193
194 // Update a range of bits, using a hint about the size. Currently only
195 // inlines the predominant case of a 1-bit range. Works best when hint is a
196 // compile-time constant.
197 void set_range(idx_t beg, idx_t end, RangeSizeHint hint);
198 void clear_range(idx_t beg, idx_t end, RangeSizeHint hint);
199 void par_set_range(idx_t beg, idx_t end, RangeSizeHint hint);
200 void par_clear_range (idx_t beg, idx_t end, RangeSizeHint hint);
201
202 // Clearing
203 void clear_large();
204 inline void clear();
205
206 // Iteration support. Returns "true" if the iteration completed, false
207 // if the iteration terminated early (because the closure "blk" returned
208 // false).
209 bool iterate(BitMapClosure* blk, idx_t leftIndex, idx_t rightIndex);
210 bool iterate(BitMapClosure* blk) {
211 // call the version that takes an interval
212 return iterate(blk, 0, size());
213 }
214
215 // Looking for 1's and 0's at indices equal to or greater than "l_index",
216 // stopping if none has been found before "r_index", and returning
217 // "r_index" (which must be at most "size") in that case.
218 idx_t get_next_one_offset_inline (idx_t l_index, idx_t r_index) const;
219 idx_t get_next_zero_offset_inline(idx_t l_index, idx_t r_index) const;
220
221 // Like "get_next_one_offset_inline", except requires that "r_index" is
222 // aligned to bitsizeof(bm_word_t).
223 idx_t get_next_one_offset_inline_aligned_right(idx_t l_index,
224 idx_t r_index) const;
225
226 // Non-inline versionsof the above.
227 idx_t get_next_one_offset (idx_t l_index, idx_t r_index) const;
228 idx_t get_next_zero_offset(idx_t l_index, idx_t r_index) const;
229
230 idx_t get_next_one_offset(idx_t offset) const {
231 return get_next_one_offset(offset, size());
232 }
233 idx_t get_next_zero_offset(idx_t offset) const {
234 return get_next_zero_offset(offset, size());
235 }
236
237 // Returns the number of bits set in the bitmap.
238 idx_t count_one_bits() const;
239
240 // Set operations.
241 void set_union(BitMap bits);
242 void set_difference(BitMap bits);
243 void set_intersection(BitMap bits);
244 // Returns true iff "this" is a superset of "bits".
245 bool contains(const BitMap bits) const;
246 // Returns true iff "this and "bits" have a non-empty intersection.
247 bool intersects(const BitMap bits) const;
248
249 // Returns result of whether this map changed
250 // during the operation
251 bool set_union_with_result(BitMap bits);
252 bool set_difference_with_result(BitMap bits);
253 bool set_intersection_with_result(BitMap bits);
254
255 // Requires the submap of "bits" starting at offset to be at least as
256 // large as "this". Modifies "this" to be the intersection of its
257 // current contents and the submap of "bits" starting at "offset" of the
258 // same length as "this."
259 // (For expedience, currently requires the offset to be aligned to the
260 // bitsize of a uintptr_t. This should go away in the future though it
261 // will probably remain a good case to optimize.)
262 void set_intersection_at_offset(BitMap bits, idx_t offset);
263
264 void set_from(BitMap bits);
265
266 bool is_same(BitMap bits);
267
268 // Test if all bits are set or cleared
269 bool is_full() const;
270 bool is_empty() const;
271
272 void print_on_error(outputStream* st, const char* prefix) const;
273
274 #ifndef PRODUCT
275 public:
276 // Printing
277 void print_on(outputStream* st) const;
278 #endif
279 };
280
281 // Convenience class wrapping BitMap which provides multiple bits per slot.
282 class BitMap2D VALUE_OBJ_CLASS_SPEC {
283 public:
284 typedef BitMap::idx_t idx_t; // Type used for bit and word indices.
285 typedef BitMap::bm_word_t bm_word_t; // Element type of array that
286 // represents the bitmap.
287 private:
288 BitMap _map;
289 idx_t _bits_per_slot;
290
291 idx_t bit_index(idx_t slot_index, idx_t bit_within_slot_index) const {
292 return slot_index * _bits_per_slot + bit_within_slot_index;
293 }
294
295 void verify_bit_within_slot_index(idx_t index) const {
296 assert(index < _bits_per_slot, "bit_within_slot index out of bounds");
297 }
298
299 public:
300 // Construction. bits_per_slot must be greater than 0.
301 BitMap2D(bm_word_t* map, idx_t size_in_slots, idx_t bits_per_slot);
302
303 // Allocates necessary data structure in resource area. bits_per_slot must be greater than 0.
304 BitMap2D(idx_t size_in_slots, idx_t bits_per_slot);
305
306 idx_t size_in_bits() {
307 return _map.size();
308 }
309
310 // Returns number of full slots that have been allocated
311 idx_t size_in_slots() {
312 // Round down
313 return _map.size() / _bits_per_slot;
314 }
315
316 bool is_valid_index(idx_t slot_index, idx_t bit_within_slot_index) {
317 verify_bit_within_slot_index(bit_within_slot_index);
318 return (bit_index(slot_index, bit_within_slot_index) < size_in_bits());
319 }
320
321 bool at(idx_t slot_index, idx_t bit_within_slot_index) const {
322 verify_bit_within_slot_index(bit_within_slot_index);
323 return _map.at(bit_index(slot_index, bit_within_slot_index));
324 }
325
326 void set_bit(idx_t slot_index, idx_t bit_within_slot_index) {
327 verify_bit_within_slot_index(bit_within_slot_index);
328 _map.set_bit(bit_index(slot_index, bit_within_slot_index));
329 }
330
331 void clear_bit(idx_t slot_index, idx_t bit_within_slot_index) {
332 verify_bit_within_slot_index(bit_within_slot_index);
333 _map.clear_bit(bit_index(slot_index, bit_within_slot_index));
334 }
335
336 void at_put(idx_t slot_index, idx_t bit_within_slot_index, bool value) {
337 verify_bit_within_slot_index(bit_within_slot_index);
338 _map.at_put(bit_index(slot_index, bit_within_slot_index), value);
339 }
340
341 void at_put_grow(idx_t slot_index, idx_t bit_within_slot_index, bool value) {
342 verify_bit_within_slot_index(bit_within_slot_index);
343 _map.at_put_grow(bit_index(slot_index, bit_within_slot_index), value);
344 }
345
346 void clear();
347 };
348
349 // Closure for iterating over BitMaps
350
351 class BitMapClosure VALUE_OBJ_CLASS_SPEC {
352 public:
353 // Callback when bit in map is set. Should normally return "true";
354 // return of false indicates that the bitmap iteration should terminate.
355 virtual bool do_bit(BitMap::idx_t offset) = 0;
356 };
357
358 #endif // SHARE_VM_UTILITIES_BITMAP_HPP