forked from arminbiere/kissat
-
Notifications
You must be signed in to change notification settings - Fork 0
/
decide.c
237 lines (209 loc) · 5.98 KB
/
decide.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
#include "decide.h"
#include "inlineframes.h"
#include "inlineheap.h"
#include "inlinequeue.h"
#include "print.h"
#include <inttypes.h>
static unsigned last_enqueued_unassigned_variable (kissat *solver) {
assert (solver->unassigned);
const links *const links = solver->links;
const value *const values = solver->values;
unsigned res = solver->queue.search.idx;
if (values[LIT (res)]) {
do {
res = links[res].prev;
assert (!DISCONNECTED (res));
} while (values[LIT (res)]);
kissat_update_queue (solver, links, res);
}
#ifdef LOGGING
const unsigned stamp = links[res].stamp;
LOG ("last enqueued unassigned %s stamp %u", LOGVAR (res), stamp);
#endif
#ifdef CHECK_QUEUE
for (unsigned i = links[res].next; !DISCONNECTED (i); i = links[i].next)
assert (VALUE (LIT (i)));
#endif
return res;
}
static unsigned largest_score_unassigned_variable (kissat *solver) {
heap *scores = SCORES;
unsigned res = kissat_max_heap (scores);
const value *const values = solver->values;
while (values[LIT (res)]) {
kissat_pop_max_heap (solver, scores);
res = kissat_max_heap (scores);
}
#if defined(LOGGING) || defined(CHECK_HEAP)
const double score = kissat_get_heap_score (scores, res);
#endif
LOG ("largest score unassigned %s score %g", LOGVAR (res), score);
#ifdef CHECK_HEAP
for (all_variables (idx)) {
if (!ACTIVE (idx))
continue;
if (VALUE (LIT (idx)))
continue;
const double idx_score = kissat_get_heap_score (scores, idx);
assert (score >= idx_score);
}
#endif
return res;
}
void kissat_start_random_sequence (kissat *solver) {
if (!GET_OPTION (randec))
return;
if (solver->stable && !GET_OPTION (randecstable))
return;
if (!solver->stable && !GET_OPTION (randecfocused))
return;
if (solver->randec)
kissat_very_verbose (solver,
"continuing random decision sequence "
"at %s conflicts",
FORMAT_COUNT (CONFLICTS));
else {
INC (random_sequences);
const uint64_t count = solver->statistics.random_sequences;
const unsigned length = GET_OPTION (randeclength) * LOGN (count);
kissat_very_verbose (solver,
"starting random decision sequence "
"at %s conflicts for %s conflicts",
FORMAT_COUNT (CONFLICTS), FORMAT_COUNT (length));
solver->randec = length;
UPDATE_CONFLICT_LIMIT (randec, random_sequences, LOGN, false);
}
}
static unsigned next_random_decision (kissat *solver) {
if (!VARS)
return INVALID_IDX;
if (!GET_OPTION (randec))
return INVALID_IDX;
if (solver->stable && !GET_OPTION (randecstable))
return INVALID_IDX;
if (!solver->stable && !GET_OPTION (randecfocused))
return INVALID_IDX;
if (!solver->randec) {
assert (solver->level);
if (solver->level > 1)
return INVALID_IDX;
uint64_t conflicts = CONFLICTS;
limits *limits = &solver->limits;
if (conflicts < limits->randec.conflicts)
return INVALID_IDX;
kissat_start_random_sequence (solver);
}
for (;;) {
unsigned idx = kissat_next_random32 (&solver->random) % VARS;
if (!ACTIVE (idx))
continue;
unsigned lit = LIT (idx);
if (solver->values[lit])
continue;
return idx;
}
}
static unsigned kissat_next_decision_variable (kissat *solver) {
#ifdef LOGGING
const char *type = 0;
#endif
unsigned res = next_random_decision (solver);
if (res == INVALID_IDX) {
if (solver->stable) {
#ifdef LOGGING
type = "maximum score";
#endif
res = largest_score_unassigned_variable (solver);
INC (score_decisions);
} else {
#ifdef LOGGING
type = "dequeued";
#endif
res = last_enqueued_unassigned_variable (solver);
INC (queue_decisions);
}
} else {
#ifdef LOGGING
type = "random";
#endif
INC (random_decisions);
}
LOG ("next %s decision %s", type, LOGVAR (res));
return res;
}
static inline value decide_phase (kissat *solver, unsigned idx) {
bool force = GET_OPTION (forcephase);
value *target;
if (force)
target = 0;
else if (!GET_OPTION (target))
target = 0;
else if (solver->stable || GET_OPTION (target) > 1)
target = solver->phases.target + idx;
else
target = 0;
value *saved;
if (force)
saved = 0;
else if (GET_OPTION (phasesaving))
saved = solver->phases.saved + idx;
else
saved = 0;
value res = 0;
if (!solver->stable) {
switch ((solver->statistics.switched >> 1) & 7) {
case 1:
res = INITIAL_PHASE;
break;
case 3:
res = -INITIAL_PHASE;
break;
}
}
if (!res && target && (res = *target)) {
LOG ("%s uses target decision phase %d", LOGVAR (idx), (int) res);
INC (target_decisions);
}
if (!res && saved && (res = *saved)) {
LOG ("%s uses saved decision phase %d", LOGVAR (idx), (int) res);
INC (saved_decisions);
}
if (!res) {
res = INITIAL_PHASE;
LOG ("%s uses initial decision phase %d", LOGVAR (idx), (int) res);
INC (initial_decisions);
}
assert (res);
return res;
}
void kissat_decide (kissat *solver) {
START (decide);
assert (solver->unassigned);
INC (decisions);
if (solver->stable)
INC (stable_decisions);
else
INC (focused_decisions);
solver->level++;
assert (solver->level != INVALID_LEVEL);
const unsigned idx = kissat_next_decision_variable (solver);
const value value = decide_phase (solver, idx);
unsigned lit = LIT (idx);
if (value < 0)
lit = NOT (lit);
kissat_push_frame (solver, lit);
assert (solver->level < SIZE_STACK (solver->frames));
LOG ("decide literal %s", LOGLIT (lit));
kissat_assign_decision (solver, lit);
STOP (decide);
}
void kissat_internal_assume (kissat *solver, unsigned lit) {
assert (solver->unassigned);
assert (!VALUE (lit));
solver->level++;
assert (solver->level != INVALID_LEVEL);
kissat_push_frame (solver, lit);
assert (solver->level < SIZE_STACK (solver->frames));
LOG ("assuming literal %s", LOGLIT (lit));
kissat_assign_decision (solver, lit);
}