1 /* Simple bitmaps.
2 Copyright (C) 1999-2023 Free Software Foundation, Inc.
3
4 This file is part of GCC.
5
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
10
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
19
20 #ifndef GCC_SBITMAP_H
21 #define GCC_SBITMAP_H
22
23 /* Implementation of sets using simple bitmap vectors.
24
25 This set representation is suitable for non-sparse sets with a known
26 (a priori) universe. The set is represented as a simple array of the
27 host's fastest unsigned integer. For a given member I in the set:
28 - the element for I will be at sbitmap[I / (bits per element)]
29 - the position for I within element is I % (bits per element)
30
31 This representation is very space-efficient for large non-sparse sets
32 with random access patterns.
33
34 The following operations can be performed in O(1) time:
35
36 * set_size : SBITMAP_SIZE
37 * member_p : bitmap_bit_p
38 * add_member : bitmap_set_bit
39 * remove_member : bitmap_clear_bit
40
41 Most other operations on this set representation are O(U) where U is
42 the size of the set universe:
43
44 * clear : bitmap_clear
45 * choose_one : bitmap_first_set_bit /
46 bitmap_last_set_bit
47 * forall : EXECUTE_IF_SET_IN_BITMAP
48 * set_copy : bitmap_copy
49 * set_intersection : bitmap_and
50 * set_union : bitmap_ior
51 * set_difference : bitmap_and_compl
52 * set_disjuction : (not implemented)
53 * set_compare : bitmap_equal_p
54 * bit_in_range_p : bitmap_bit_in_range_p
55
56 Some operations on 3 sets that occur frequently in data flow problems
57 are also implemented:
58
59 * A | (B & C) : bitmap_or_and
60 * A | (B & ~C) : bitmap_ior_and_compl
61 * A & (B | C) : bitmap_and_or
62
63 Most of the set functions have two variants: One that returns non-zero
64 if members were added or removed from the target set, and one that just
65 performs the operation without feedback. The former operations are a
66 bit more expensive but the result can often be used to avoid iterations
67 on other sets.
68
69 Allocating a bitmap is done with sbitmap_alloc, and resizing is
70 performed with sbitmap_resize.
71
72 The storage requirements for simple bitmap sets is O(U) where U is the
73 size of the set universe (colloquially the number of bits in the bitmap).
74
75 This set representation works well for relatively small data flow problems
76 (there are special routines for that, see sbitmap_vector_*). The set
77 operations can be vectorized and there is almost no computating overhead,
78 so that even sparse simple bitmap sets outperform dedicated sparse set
79 representations like linked-list bitmaps. For larger problems, the size
80 overhead of simple bitmap sets gets too high and other set representations
81 have to be used. */
82
83 #define SBITMAP_ELT_BITS (HOST_BITS_PER_WIDEST_FAST_INT * 1u)
84 #define SBITMAP_ELT_TYPE unsigned HOST_WIDEST_FAST_INT
85
86 struct simple_bitmap_def
87 {
88 unsigned int n_bits; /* Number of bits. */
89 unsigned int size; /* Size in elements. */
90 SBITMAP_ELT_TYPE elms[1]; /* The elements. */
91 };
92
93 /* Return the set size needed for N elements. */
94 #define SBITMAP_SET_SIZE(N) (((N) + SBITMAP_ELT_BITS - 1) / SBITMAP_ELT_BITS)
95
96 /* Return the number of bits in BITMAP. */
97 #define SBITMAP_SIZE(BITMAP) ((BITMAP)->n_bits)
98
99 /* Verify that access at INDEX in bitmap MAP is valid. */
100
101 inline void
102 bitmap_check_index (const_sbitmap map, int index)
103 {
104 gcc_checking_assert (index >= 0);
105 gcc_checking_assert ((unsigned int)index < map->n_bits);
106 }
107
108 /* Verify that bitmaps A and B have same size. */
109
110 inline void
111 bitmap_check_sizes (const_sbitmap a, const_sbitmap b)
112 {
113 gcc_checking_assert (a->n_bits == b->n_bits);
114 }
115
116 /* Test if bit number bitno in the bitmap is set. */
117 inline bool
118 bitmap_bit_p (const_sbitmap map, int bitno)
119 {
120 bitmap_check_index (map, bitno);
121
122 size_t i = bitno / SBITMAP_ELT_BITS;
123 unsigned int s = bitno % SBITMAP_ELT_BITS;
124 return (map->elms[i] >> s) & (SBITMAP_ELT_TYPE) 1;
125 }
126
127 /* Set bit number BITNO in the sbitmap MAP.
128 Return true if the bit changed. */
129
130 inline bool
131 bitmap_set_bit (sbitmap map, int bitno)
132 {
133 bitmap_check_index (map, bitno);
134
135 size_t i = bitno / SBITMAP_ELT_BITS;
136 unsigned int s = bitno % SBITMAP_ELT_BITS;
137 if (map->elms[i] & ((SBITMAP_ELT_TYPE) 1 << s))
138 return false;
139 map->elms[i] |= (SBITMAP_ELT_TYPE) 1 << s;
140 return true;
141 }
142
143 /* Reset bit number BITNO in the sbitmap MAP.
144 Return true if the bit changed. */
145
146 inline bool
147 bitmap_clear_bit (sbitmap map, int bitno)
148 {
149 bitmap_check_index (map, bitno);
150
151 size_t i = bitno / SBITMAP_ELT_BITS;
152 unsigned int s = bitno % SBITMAP_ELT_BITS;
153 if (!(map->elms[i] & ((SBITMAP_ELT_TYPE) 1 << s)))
154 return false;
155 map->elms[i] &= ~((SBITMAP_ELT_TYPE) 1 << s);
156 return true;
157 }
158
159 /* The iterator for sbitmap. */
160 struct sbitmap_iterator {
161 /* The pointer to the first word of the bitmap. */
162 const SBITMAP_ELT_TYPE *ptr;
163
164 /* The size of the bitmap. */
165 unsigned int size;
166
167 /* The current word index. */
168 unsigned int word_num;
169
170 /* The current bit index (not modulo SBITMAP_ELT_BITS). */
171 unsigned int bit_num;
172
173 /* The words currently visited. */
174 SBITMAP_ELT_TYPE word;
175 };
176
177 /* Initialize the iterator I with sbitmap BMP and the initial index
178 MIN. */
179
180 inline void
181 bmp_iter_set_init (sbitmap_iterator *i, const_sbitmap bmp,
182 unsigned int min, unsigned *bit_no ATTRIBUTE_UNUSED)
183 {
184 i->word_num = min / (unsigned int) SBITMAP_ELT_BITS;
185 i->bit_num = min;
186 i->size = bmp->size;
187 i->ptr = bmp->elms;
188
189 if (i->word_num >= i->size)
190 i->word = 0;
191 else
192 i->word = (i->ptr[i->word_num]
193 >> (i->bit_num % (unsigned int) SBITMAP_ELT_BITS));
194 }
195
196 /* Return true if we have more bits to visit, in which case *N is set
197 to the index of the bit to be visited. Otherwise, return
198 false. */
199
200 inline bool
201 bmp_iter_set (sbitmap_iterator *i, unsigned int *n)
202 {
203 /* Skip words that are zeros. */
204 for (; i->word == 0; i->word = i->ptr[i->word_num])
205 {
206 i->word_num++;
207
208 /* If we have reached the end, break. */
209 if (i->word_num >= i->size)
210 return false;
211
212 i->bit_num = i->word_num * SBITMAP_ELT_BITS;
213 }
214
215 /* Skip bits that are zero. */
216 for (; (i->word & 1) == 0; i->word >>= 1)
217 i->bit_num++;
218
219 *n = i->bit_num;
220
221 return true;
222 }
223
224 /* Advance to the next bit. */
225
226 inline void
227 bmp_iter_next (sbitmap_iterator *i, unsigned *bit_no ATTRIBUTE_UNUSED)
228 {
229 i->word >>= 1;
230 i->bit_num++;
231 }
232
233 /* Loop over all elements of SBITMAP, starting with MIN. In each
234 iteration, N is set to the index of the bit being visited. ITER is
235 an instance of sbitmap_iterator used to iterate the bitmap. */
236
237 #ifndef EXECUTE_IF_SET_IN_BITMAP
238 /* See bitmap.h for the other definition of EXECUTE_IF_SET_IN_BITMAP. */
239 #define EXECUTE_IF_SET_IN_BITMAP(BITMAP, MIN, BITNUM, ITER) \
240 for (bmp_iter_set_init (&(ITER), (BITMAP), (MIN), &(BITNUM)); \
241 bmp_iter_set (&(ITER), &(BITNUM)); \
242 bmp_iter_next (&(ITER), &(BITNUM)))
243 #endif
244
245 inline void sbitmap_free (sbitmap map)
246 {
247 free (map);
248 }
249
250 inline void sbitmap_vector_free (sbitmap * vec)
251 {
252 free (vec);
253 }
254
255 extern void dump_bitmap (FILE *, const_sbitmap);
256 extern void debug_raw (const simple_bitmap_def &ref);
257 extern void debug_raw (const simple_bitmap_def *ptr);
258 extern void dump_bitmap_file (FILE *, const_sbitmap);
259 extern void debug (const simple_bitmap_def &ref);
260 extern void debug (const simple_bitmap_def *ptr);
261 extern void dump_bitmap_vector (FILE *, const char *, const char *, sbitmap *,
262 int);
263 extern sbitmap sbitmap_alloc (unsigned int);
264 extern sbitmap *sbitmap_vector_alloc (unsigned int, unsigned int);
265 extern sbitmap sbitmap_resize (sbitmap, unsigned int, int);
266 extern void bitmap_copy (sbitmap, const_sbitmap);
267 extern int bitmap_equal_p (const_sbitmap, const_sbitmap);
268 extern unsigned int bitmap_count_bits (const_sbitmap);
269 extern bool bitmap_empty_p (const_sbitmap);
270 extern void bitmap_clear (sbitmap);
271 extern void bitmap_clear_range (sbitmap, unsigned, unsigned);
272 extern void bitmap_set_range (sbitmap, unsigned, unsigned);
273 extern void bitmap_ones (sbitmap);
274 extern void bitmap_vector_clear (sbitmap *, unsigned int);
275 extern void bitmap_vector_ones (sbitmap *, unsigned int);
276
277 extern bool bitmap_ior_and_compl (sbitmap, const_sbitmap,
278 const_sbitmap, const_sbitmap);
279 extern void bitmap_and_compl (sbitmap, const_sbitmap, const_sbitmap);
280 extern void bitmap_not (sbitmap, const_sbitmap);
281 extern bool bitmap_or_and (sbitmap, const_sbitmap,
282 const_sbitmap, const_sbitmap);
283 extern bool bitmap_and_or (sbitmap, const_sbitmap,
284 const_sbitmap, const_sbitmap);
285 extern bool bitmap_intersect_p (const_sbitmap, const_sbitmap);
286 extern bool bitmap_and (sbitmap, const_sbitmap, const_sbitmap);
287 extern bool bitmap_ior (sbitmap, const_sbitmap, const_sbitmap);
288 extern bool bitmap_xor (sbitmap, const_sbitmap, const_sbitmap);
289 extern bool bitmap_subset_p (const_sbitmap, const_sbitmap);
290 extern bool bitmap_bit_in_range_p (const_sbitmap, unsigned int, unsigned int);
291
292 extern int bitmap_first_set_bit (const_sbitmap);
293 extern int bitmap_last_set_bit (const_sbitmap);
294
295 extern void debug_bitmap (const_sbitmap);
296 extern sbitmap sbitmap_realloc (sbitmap, unsigned int);
297
298 /* a class that ties the lifetime of a sbitmap to its scope. */
299 class auto_sbitmap
300 {
301 public:
302 explicit auto_sbitmap (unsigned int size) :
303 m_bitmap (sbitmap_alloc (size)) {}
304 ~auto_sbitmap () { sbitmap_free (m_bitmap); }
305
306 /* Allow calling sbitmap functions on our bitmap. */
307 operator sbitmap () { return m_bitmap; }
308 operator const_sbitmap () const { return m_bitmap; }
309
310 private:
311 /* Prevent making a copy that refers to our sbitmap. */
312 auto_sbitmap (const auto_sbitmap &);
313 auto_sbitmap &operator = (const auto_sbitmap &);
314 auto_sbitmap (auto_sbitmap &&);
315 auto_sbitmap &operator = (auto_sbitmap &&);
316
317 /* The bitmap we are managing. */
318 sbitmap m_bitmap;
319 };
320
321 #endif /* ! GCC_SBITMAP_H */