0
|
1 /* Set operations on pointers
|
|
2 Copyright (C) 2004, 2006, 2007 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
|
|
7 it under the terms of the GNU General Public License as published by
|
|
8 the Free Software Foundation; either version 3, or (at your option)
|
|
9 any later version.
|
|
10
|
|
11 GCC is distributed in the hope that it will be useful,
|
|
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
14 GNU General Public License 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 #include "config.h"
|
|
21 #include "system.h"
|
|
22 #include "pointer-set.h"
|
|
23
|
|
24 /* A pointer set is represented as a simple open-addressing hash
|
|
25 table. Simplifications: The hash code is based on the value of the
|
|
26 pointer, not what it points to. The number of buckets is always a
|
|
27 power of 2. Null pointers are a reserved value. Deletion is not
|
|
28 supported (yet). There is no mechanism for user control of hash
|
|
29 function, equality comparison, initial size, or resizing policy. */
|
|
30
|
|
31 struct pointer_set_t
|
|
32 {
|
|
33 size_t log_slots;
|
|
34 size_t n_slots; /* n_slots = 2^log_slots */
|
|
35 size_t n_elements;
|
|
36
|
|
37 const void **slots;
|
|
38 };
|
|
39
|
|
40 /* Use the multiplicative method, as described in Knuth 6.4, to obtain
|
|
41 a hash code for P in the range [0, MAX). MAX == 2^LOGMAX.
|
|
42
|
|
43 Summary of this method: Multiply p by some number A that's
|
|
44 relatively prime to 2^sizeof(size_t). The result is two words.
|
|
45 Discard the most significant word, and return the most significant
|
|
46 N bits of the least significant word. As suggested by Knuth, our
|
|
47 choice for A is the integer part of (ULONG_MAX + 1.0) / phi, where phi
|
|
48 is the golden ratio.
|
|
49
|
|
50 We don't need to do anything special for full-width multiplication
|
|
51 because we're only interested in the least significant word of the
|
|
52 product, and unsigned arithmetic in C is modulo the word size. */
|
|
53
|
|
54 static inline size_t
|
|
55 hash1 (const void *p, unsigned long max, unsigned long logmax)
|
|
56 {
|
|
57 #if HOST_BITS_PER_LONG == 32
|
|
58 const unsigned long A = 0x9e3779b9u;
|
|
59 #elif HOST_BITS_PER_LONG == 64
|
|
60 const unsigned long A = 0x9e3779b97f4a7c16ul;
|
|
61 #else
|
|
62 const unsigned long A
|
|
63 = (ULONG_MAX + 1.0L) * 0.6180339887498948482045868343656381177203L;
|
|
64 #endif
|
|
65 const unsigned long shift = HOST_BITS_PER_LONG - logmax;
|
|
66
|
|
67 return ((A * (unsigned long) p) >> shift) & (max - 1);
|
|
68 }
|
|
69
|
|
70 /* Allocate an empty pointer set. */
|
|
71 struct pointer_set_t *
|
|
72 pointer_set_create (void)
|
|
73 {
|
|
74 struct pointer_set_t *result = XNEW (struct pointer_set_t);
|
|
75
|
|
76 result->n_elements = 0;
|
|
77 result->log_slots = 8;
|
|
78 result->n_slots = (size_t) 1 << result->log_slots;
|
|
79
|
|
80 result->slots = XCNEWVEC (const void *, result->n_slots);
|
|
81 return result;
|
|
82 }
|
|
83
|
|
84 /* Reclaims all memory associated with PSET. */
|
|
85 void
|
|
86 pointer_set_destroy (struct pointer_set_t *pset)
|
|
87 {
|
|
88 XDELETEVEC (pset->slots);
|
|
89 XDELETE (pset);
|
|
90 }
|
|
91
|
|
92 /* Returns nonzero if PSET contains P. P must be nonnull.
|
|
93
|
|
94 Collisions are resolved by linear probing. */
|
|
95 int
|
|
96 pointer_set_contains (const struct pointer_set_t *pset, const void *p)
|
|
97 {
|
|
98 size_t n = hash1 (p, pset->n_slots, pset->log_slots);
|
|
99
|
|
100 while (true)
|
|
101 {
|
|
102 if (pset->slots[n] == p)
|
|
103 return 1;
|
|
104 else if (pset->slots[n] == 0)
|
|
105 return 0;
|
|
106 else
|
|
107 {
|
|
108 ++n;
|
|
109 if (n == pset->n_slots)
|
|
110 n = 0;
|
|
111 }
|
|
112 }
|
|
113 }
|
|
114
|
|
115 /* Subroutine of pointer_set_insert. Return the insertion slot for P into
|
|
116 an empty element of SLOTS, an array of length N_SLOTS. */
|
|
117 static inline size_t
|
|
118 insert_aux (const void *p, const void **slots, size_t n_slots, size_t log_slots)
|
|
119 {
|
|
120 size_t n = hash1 (p, n_slots, log_slots);
|
|
121 while (true)
|
|
122 {
|
|
123 if (slots[n] == p || slots[n] == 0)
|
|
124 return n;
|
|
125 else
|
|
126 {
|
|
127 ++n;
|
|
128 if (n == n_slots)
|
|
129 n = 0;
|
|
130 }
|
|
131 }
|
|
132 }
|
|
133
|
|
134 /* Inserts P into PSET if it wasn't already there. Returns nonzero
|
|
135 if it was already there. P must be nonnull. */
|
|
136 int
|
|
137 pointer_set_insert (struct pointer_set_t *pset, const void *p)
|
|
138 {
|
|
139 size_t n;
|
|
140
|
|
141 /* For simplicity, expand the set even if P is already there. This can be
|
|
142 superfluous but can happen at most once. */
|
|
143 if (pset->n_elements > pset->n_slots / 4)
|
|
144 {
|
|
145 size_t new_log_slots = pset->log_slots + 1;
|
|
146 size_t new_n_slots = pset->n_slots * 2;
|
|
147 const void **new_slots = XCNEWVEC (const void *, new_n_slots);
|
|
148 size_t i;
|
|
149
|
|
150 for (i = 0; i < pset->n_slots; ++i)
|
|
151 {
|
|
152 const void *value = pset->slots[i];
|
|
153 n = insert_aux (value, new_slots, new_n_slots, new_log_slots);
|
|
154 new_slots[n] = value;
|
|
155 }
|
|
156
|
|
157 XDELETEVEC (pset->slots);
|
|
158 pset->n_slots = new_n_slots;
|
|
159 pset->log_slots = new_log_slots;
|
|
160 pset->slots = new_slots;
|
|
161 }
|
|
162
|
|
163 n = insert_aux (p, pset->slots, pset->n_slots, pset->log_slots);
|
|
164 if (pset->slots[n])
|
|
165 return 1;
|
|
166
|
|
167 pset->slots[n] = p;
|
|
168 ++pset->n_elements;
|
|
169 return 0;
|
|
170 }
|
|
171
|
|
172 /* Pass each pointer in PSET to the function in FN, together with the fixed
|
|
173 parameter DATA. If FN returns false, the iteration stops. */
|
|
174
|
|
175 void pointer_set_traverse (const struct pointer_set_t *pset,
|
|
176 bool (*fn) (const void *, void *), void *data)
|
|
177 {
|
|
178 size_t i;
|
|
179 for (i = 0; i < pset->n_slots; ++i)
|
|
180 if (pset->slots[i] && !fn (pset->slots[i], data))
|
|
181 break;
|
|
182 }
|
|
183
|
|
184
|
|
185 /* A pointer map is represented the same way as a pointer_set, so
|
|
186 the hash code is based on the address of the key, rather than
|
|
187 its contents. Null keys are a reserved value. Deletion is not
|
|
188 supported (yet). There is no mechanism for user control of hash
|
|
189 function, equality comparison, initial size, or resizing policy. */
|
|
190
|
|
191 struct pointer_map_t
|
|
192 {
|
|
193 size_t log_slots;
|
|
194 size_t n_slots; /* n_slots = 2^log_slots */
|
|
195 size_t n_elements;
|
|
196
|
|
197 const void **keys;
|
|
198 void **values;
|
|
199 };
|
|
200
|
|
201 /* Allocate an empty pointer map. */
|
|
202 struct pointer_map_t *
|
|
203 pointer_map_create (void)
|
|
204 {
|
|
205 struct pointer_map_t *result = XNEW (struct pointer_map_t);
|
|
206
|
|
207 result->n_elements = 0;
|
|
208 result->log_slots = 8;
|
|
209 result->n_slots = (size_t) 1 << result->log_slots;
|
|
210
|
|
211 result->keys = XCNEWVEC (const void *, result->n_slots);
|
|
212 result->values = XCNEWVEC (void *, result->n_slots);
|
|
213 return result;
|
|
214 }
|
|
215
|
|
216 /* Reclaims all memory associated with PMAP. */
|
|
217 void pointer_map_destroy (struct pointer_map_t *pmap)
|
|
218 {
|
|
219 XDELETEVEC (pmap->keys);
|
|
220 XDELETEVEC (pmap->values);
|
|
221 XDELETE (pmap);
|
|
222 }
|
|
223
|
|
224 /* Returns a pointer to the value to which P maps, if PMAP contains P. P
|
|
225 must be nonnull. Return NULL if PMAP does not contain P.
|
|
226
|
|
227 Collisions are resolved by linear probing. */
|
|
228 void **
|
|
229 pointer_map_contains (const struct pointer_map_t *pmap, const void *p)
|
|
230 {
|
|
231 size_t n = hash1 (p, pmap->n_slots, pmap->log_slots);
|
|
232
|
|
233 while (true)
|
|
234 {
|
|
235 if (pmap->keys[n] == p)
|
|
236 return &pmap->values[n];
|
|
237 else if (pmap->keys[n] == 0)
|
|
238 return NULL;
|
|
239 else
|
|
240 {
|
|
241 ++n;
|
|
242 if (n == pmap->n_slots)
|
|
243 n = 0;
|
|
244 }
|
|
245 }
|
|
246 }
|
|
247
|
|
248 /* Inserts P into PMAP if it wasn't already there. Returns a pointer
|
|
249 to the value. P must be nonnull. */
|
|
250 void **
|
|
251 pointer_map_insert (struct pointer_map_t *pmap, const void *p)
|
|
252 {
|
|
253 size_t n;
|
|
254
|
|
255 /* For simplicity, expand the map even if P is already there. This can be
|
|
256 superfluous but can happen at most once. */
|
|
257 if (pmap->n_elements > pmap->n_slots / 4)
|
|
258 {
|
|
259 size_t new_log_slots = pmap->log_slots + 1;
|
|
260 size_t new_n_slots = pmap->n_slots * 2;
|
|
261 const void **new_keys = XCNEWVEC (const void *, new_n_slots);
|
|
262 void **new_values = XCNEWVEC (void *, new_n_slots);
|
|
263 size_t i;
|
|
264
|
|
265 for (i = 0; i < pmap->n_slots; ++i)
|
|
266 if (pmap->keys[i])
|
|
267 {
|
|
268 const void *key = pmap->keys[i];
|
|
269 n = insert_aux (key, new_keys, new_n_slots, new_log_slots);
|
|
270 new_keys[n] = key;
|
|
271 new_values[n] = pmap->values[i];
|
|
272 }
|
|
273
|
|
274 XDELETEVEC (pmap->keys);
|
|
275 XDELETEVEC (pmap->values);
|
|
276 pmap->n_slots = new_n_slots;
|
|
277 pmap->log_slots = new_log_slots;
|
|
278 pmap->keys = new_keys;
|
|
279 pmap->values = new_values;
|
|
280 }
|
|
281
|
|
282 n = insert_aux (p, pmap->keys, pmap->n_slots, pmap->log_slots);
|
|
283 if (!pmap->keys[n])
|
|
284 {
|
|
285 ++pmap->n_elements;
|
|
286 pmap->keys[n] = p;
|
|
287 }
|
|
288
|
|
289 return &pmap->values[n];
|
|
290 }
|
|
291
|
|
292 /* Pass each pointer in PMAP to the function in FN, together with the pointer
|
|
293 to the value and the fixed parameter DATA. If FN returns false, the
|
|
294 iteration stops. */
|
|
295
|
|
296 void pointer_map_traverse (const struct pointer_map_t *pmap,
|
|
297 bool (*fn) (const void *, void **, void *), void *data)
|
|
298 {
|
|
299 size_t i;
|
|
300 for (i = 0; i < pmap->n_slots; ++i)
|
|
301 if (pmap->keys[i] && !fn (pmap->keys[i], &pmap->values[i], data))
|
|
302 break;
|
|
303 }
|