|
0
|
1 /* SparseSet implementation.
|
|
145
|
2 Copyright (C) 2007-2020 Free Software Foundation, Inc.
|
|
0
|
3 Contributed by Peter Bergner <bergner@vnet.ibm.com>
|
|
|
4
|
|
|
5 This file is part of GCC.
|
|
|
6
|
|
|
7 GCC is free software; you can redistribute it and/or modify it under
|
|
|
8 the terms of the GNU General Public License as published by the Free
|
|
|
9 Software Foundation; either version 3, or (at your option) any later
|
|
|
10 version.
|
|
|
11
|
|
|
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
|
|
|
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
|
|
|
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
|
|
|
15 for more details.
|
|
|
16
|
|
|
17 You should have received a copy of the GNU General Public License
|
|
|
18 along with GCC; see the file COPYING3. If not see
|
|
|
19 <http://www.gnu.org/licenses/>. */
|
|
|
20
|
|
|
21 #ifndef GCC_SPARSESET_H
|
|
|
22 #define GCC_SPARSESET_H
|
|
|
23
|
|
111
|
24 /* Implementation of the Briggs and Torczon sparse set representation.
|
|
|
25 The sparse set representation was first published in:
|
|
|
26
|
|
|
27 "An Efficient Representation for Sparse Sets",
|
|
|
28 ACM LOPLAS, Vol. 2, Nos. 1-4, March-December 1993, Pages 59-69.
|
|
|
29
|
|
|
30 The sparse set representation is suitable for integer sets with a
|
|
|
31 fixed-size universe. Two vectors are used to store the members of
|
|
|
32 the set. If an element I is in the set, then sparse[I] is the
|
|
|
33 index of I in the dense vector, and dense[sparse[I]] == I. The dense
|
|
|
34 vector works like a stack. The size of the stack is the cardinality
|
|
|
35 of the set.
|
|
|
36
|
|
|
37 The following operations can be performed in O(1) time:
|
|
|
38
|
|
|
39 * clear : sparseset_clear
|
|
|
40 * cardinality : sparseset_cardinality
|
|
|
41 * set_size : sparseset_size
|
|
|
42 * member_p : sparseset_bit_p
|
|
|
43 * add_member : sparseset_set_bit
|
|
|
44 * remove_member : sparseset_clear_bit
|
|
|
45 * choose_one : sparseset_pop
|
|
|
46
|
|
|
47 Additionally, the sparse set representation supports enumeration of
|
|
|
48 the members in O(N) time, where n is the number of members in the set.
|
|
|
49 The members of the set are stored cache-friendly in the dense vector.
|
|
|
50 This makes it a competitive choice for iterating over relatively sparse
|
|
|
51 sets requiring operations:
|
|
|
52
|
|
|
53 * forall : EXECUTE_IF_SET_IN_SPARSESET
|
|
|
54 * set_copy : sparseset_copy
|
|
|
55 * set_intersection : sparseset_and
|
|
|
56 * set_union : sparseset_ior
|
|
|
57 * set_difference : sparseset_and_compl
|
|
|
58 * set_disjuction : (not implemented)
|
|
|
59 * set_compare : sparseset_equal_p
|
|
|
60
|
|
|
61 NB: It is OK to use remove_member during EXECUTE_IF_SET_IN_SPARSESET.
|
|
|
62 The iterator is updated for it.
|
|
|
63
|
|
|
64 Based on the efficiency of these operations, this representation of
|
|
|
65 sparse sets will often be superior to alternatives such as simple
|
|
|
66 bitmaps, linked-list bitmaps, array bitmaps, balanced binary trees,
|
|
|
67 hash tables, linked lists, etc., if the set is sufficiently sparse.
|
|
|
68 In the LOPLAS paper the cut-off point where sparse sets became faster
|
|
|
69 than simple bitmaps (see sbitmap.h) when N / U < 64 (where U is the
|
|
|
70 size of the universe of the set).
|
|
|
71
|
|
|
72 Because the set universe is fixed, the set cannot be resized. For
|
|
|
73 sparse sets with initially unknown size, linked-list bitmaps are a
|
|
|
74 better choice, see bitmap.h.
|
|
|
75
|
|
|
76 Sparse sets storage requirements are relatively large: O(U) with a
|
|
|
77 larger constant than sbitmaps (if the storage requirement for an
|
|
|
78 sbitmap with universe U is S, then the storage required for a sparse
|
|
|
79 set for the same universe are 2*HOST_BITS_PER_WIDEST_FAST_INT * S).
|
|
|
80 Accessing the sparse vector is not very cache-friendly, but iterating
|
|
|
81 over the members in the set is cache-friendly because only the dense
|
|
|
82 vector is used. */
|
|
0
|
83
|
|
|
84 /* Data Structure used for the SparseSet representation. */
|
|
|
85
|
|
111
|
86 #define SPARSESET_ELT_BITS ((unsigned) HOST_BITS_PER_WIDEST_FAST_INT)
|
|
|
87 #define SPARSESET_ELT_TYPE unsigned HOST_WIDEST_FAST_INT
|
|
|
88
|
|
0
|
89 typedef struct sparseset_def
|
|
|
90 {
|
|
|
91 SPARSESET_ELT_TYPE *dense; /* Dense array. */
|
|
|
92 SPARSESET_ELT_TYPE *sparse; /* Sparse array. */
|
|
|
93 SPARSESET_ELT_TYPE members; /* Number of elements. */
|
|
|
94 SPARSESET_ELT_TYPE size; /* Maximum number of elements. */
|
|
|
95 SPARSESET_ELT_TYPE iter; /* Iterator index. */
|
|
|
96 unsigned char iter_inc; /* Iteration increment amount. */
|
|
|
97 bool iterating;
|
|
|
98 SPARSESET_ELT_TYPE elms[2]; /* Combined dense and sparse arrays. */
|
|
|
99 } *sparseset;
|
|
|
100
|
|
|
101 #define sparseset_free(MAP) free(MAP)
|
|
|
102 extern sparseset sparseset_alloc (SPARSESET_ELT_TYPE n_elms);
|
|
|
103 extern void sparseset_clear_bit (sparseset, SPARSESET_ELT_TYPE);
|
|
|
104 extern void sparseset_copy (sparseset, sparseset);
|
|
|
105 extern void sparseset_and (sparseset, sparseset, sparseset);
|
|
|
106 extern void sparseset_and_compl (sparseset, sparseset, sparseset);
|
|
|
107 extern void sparseset_ior (sparseset, sparseset, sparseset);
|
|
|
108 extern bool sparseset_equal_p (sparseset, sparseset);
|
|
|
109
|
|
|
110 /* Operation: S = {}
|
|
|
111 Clear the set of all elements. */
|
|
|
112
|
|
|
113 static inline void
|
|
|
114 sparseset_clear (sparseset s)
|
|
|
115 {
|
|
|
116 s->members = 0;
|
|
|
117 s->iterating = false;
|
|
|
118 }
|
|
|
119
|
|
|
120 /* Return the number of elements currently in the set. */
|
|
|
121
|
|
|
122 static inline SPARSESET_ELT_TYPE
|
|
|
123 sparseset_cardinality (sparseset s)
|
|
|
124 {
|
|
|
125 return s->members;
|
|
|
126 }
|
|
|
127
|
|
|
128 /* Return the maximum number of elements this set can hold. */
|
|
|
129
|
|
|
130 static inline SPARSESET_ELT_TYPE
|
|
|
131 sparseset_size (sparseset s)
|
|
|
132 {
|
|
|
133 return s->size;
|
|
|
134 }
|
|
|
135
|
|
|
136 /* Return true if e is a member of the set S, otherwise return false. */
|
|
|
137
|
|
|
138 static inline bool
|
|
|
139 sparseset_bit_p (sparseset s, SPARSESET_ELT_TYPE e)
|
|
|
140 {
|
|
|
141 SPARSESET_ELT_TYPE idx;
|
|
|
142
|
|
111
|
143 gcc_checking_assert (e < s->size);
|
|
0
|
144
|
|
|
145 idx = s->sparse[e];
|
|
|
146
|
|
|
147 return idx < s->members && s->dense[idx] == e;
|
|
|
148 }
|
|
|
149
|
|
|
150 /* Low level insertion routine not meant for use outside of sparseset.[ch].
|
|
|
151 Assumes E is valid and not already a member of the set S. */
|
|
|
152
|
|
|
153 static inline void
|
|
|
154 sparseset_insert_bit (sparseset s, SPARSESET_ELT_TYPE e, SPARSESET_ELT_TYPE idx)
|
|
|
155 {
|
|
|
156 s->sparse[e] = idx;
|
|
|
157 s->dense[idx] = e;
|
|
|
158 }
|
|
|
159
|
|
|
160 /* Operation: S = S + {e}
|
|
|
161 Insert E into the set S, if it isn't already a member. */
|
|
|
162
|
|
|
163 static inline void
|
|
|
164 sparseset_set_bit (sparseset s, SPARSESET_ELT_TYPE e)
|
|
|
165 {
|
|
|
166 if (!sparseset_bit_p (s, e))
|
|
|
167 sparseset_insert_bit (s, e, s->members++);
|
|
|
168 }
|
|
|
169
|
|
111
|
170 /* Return and remove the last member added to the set S. */
|
|
0
|
171
|
|
|
172 static inline SPARSESET_ELT_TYPE
|
|
|
173 sparseset_pop (sparseset s)
|
|
|
174 {
|
|
|
175 SPARSESET_ELT_TYPE mem = s->members;
|
|
|
176
|
|
111
|
177 gcc_checking_assert (mem != 0);
|
|
0
|
178
|
|
|
179 s->members = mem - 1;
|
|
111
|
180 return s->dense[s->members];
|
|
0
|
181 }
|
|
|
182
|
|
|
183 static inline void
|
|
|
184 sparseset_iter_init (sparseset s)
|
|
|
185 {
|
|
|
186 s->iter = 0;
|
|
|
187 s->iter_inc = 1;
|
|
|
188 s->iterating = true;
|
|
|
189 }
|
|
|
190
|
|
|
191 static inline bool
|
|
|
192 sparseset_iter_p (sparseset s)
|
|
|
193 {
|
|
|
194 if (s->iterating && s->iter < s->members)
|
|
|
195 return true;
|
|
|
196 else
|
|
|
197 return s->iterating = false;
|
|
|
198 }
|
|
|
199
|
|
|
200 static inline SPARSESET_ELT_TYPE
|
|
|
201 sparseset_iter_elm (sparseset s)
|
|
|
202 {
|
|
|
203 return s->dense[s->iter];
|
|
|
204 }
|
|
|
205
|
|
|
206 static inline void
|
|
|
207 sparseset_iter_next (sparseset s)
|
|
|
208 {
|
|
|
209 s->iter += s->iter_inc;
|
|
|
210 s->iter_inc = 1;
|
|
|
211 }
|
|
|
212
|
|
|
213 #define EXECUTE_IF_SET_IN_SPARSESET(SPARSESET, ITER) \
|
|
|
214 for (sparseset_iter_init (SPARSESET); \
|
|
|
215 sparseset_iter_p (SPARSESET) \
|
|
|
216 && (((ITER) = sparseset_iter_elm (SPARSESET)) || 1); \
|
|
|
217 sparseset_iter_next (SPARSESET))
|
|
|
218
|
|
|
219 #endif /* GCC_SPARSESET_H */
|
