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
|
//! Reverse unit propagation redundancy checks.
use std::ops::Range;
use partial_ref::{partial, PartialRef};
use varisat_formula::{lit::LitIdx, Lit};
use varisat_internal_proof::ClauseHash;
use crate::{
clauses::{UnitClause, UnitId},
context::{parts::*, Context},
hash::rehash,
variables::ensure_var,
CheckerError,
};
/// Propagation of the RUP check.
struct TraceItem {
id: u64,
edges: Range<usize>,
unused: bool,
}
#[derive(Default)]
pub struct RupCheck {
/// Stores overwritten values in `unit_clauses` to undo assignments.
trail: Vec<(Lit, Option<UnitClause>)>,
/// Involved clauses during the last check.
trace: Vec<TraceItem>,
/// Edges of the trace implication graph.
trace_edges: Vec<LitIdx>,
/// Just the ids of `trace`.
pub trace_ids: Vec<u64>,
}
/// Check whether a clause is implied by clauses of the given hashes.
///
/// `lits` must be sorted and free of duplicates.
pub fn check_clause_with_hashes<'a>(
mut ctx: partial!(
Context<'a>,
mut ClauseHasherP,
mut ClausesP,
mut ProcessingP<'a>,
mut RupCheckP,
mut VariablesP,
CheckerStateP,
),
lits: &[Lit],
propagation_hashes: &[ClauseHash],
) -> Result<(), CheckerError> {
if ctx.part(ClauseHasherP).rename_in_buffered_solver_var_names {
// TODO partial rehashing?
rehash(ctx.borrow());
}
let (rup, mut ctx) = ctx.split_part_mut(RupCheckP);
rup.trace.clear();
rup.trace_edges.clear();
let mut rup_is_unsat = false;
assert!(rup.trail.is_empty());
for &lit in lits.iter() {
ensure_var(ctx.borrow(), lit.var());
}
let (clauses, ctx) = ctx.split_part_mut(ClausesP);
for &lit in lits.iter() {
if let Some((true, unit)) = clauses.lit_value(lit) {
if let UnitId::Global(id) = unit.id {
rup.trace_ids.clear();
rup.trace_ids.push(id);
return Ok(());
} else {
unreachable!("unexpected non global unit");
}
}
}
// Set all lits to false
for &lit in lits.iter() {
rup.trail.push((lit, clauses.unit_clauses[lit.index()]));
clauses.unit_clauses[lit.index()] = Some(UnitClause {
value: lit.is_negative(),
id: UnitId::InClause,
});
}
'hashes: for &hash in propagation_hashes.iter() {
let candidates = match clauses.clauses.get(&hash) {
Some(candidates) if !candidates.is_empty() => candidates,
_ => {
return Err(CheckerError::check_failed(
ctx.part(CheckerStateP).step,
format!("no clause found for hash {:x}", hash),
))
}
};
// Check if any clause matching the hash propagates
'candidates: for clause in candidates.iter() {
let mut unassigned_count = 0;
let mut unassigned_lit = None;
let range_begin = rup.trace_edges.len();
for &lit in clause.lits.slice(&clauses.literal_buffer).iter() {
match clauses.lit_value(lit) {
Some((true, _)) => {
continue 'candidates;
}
Some((false, unit)) => match unit.id {
UnitId::Global(id) => {
rup.trail.push((lit, clauses.unit_clauses[lit.index()]));
clauses.unit_clauses[lit.index()] = Some(UnitClause {
value: lit.is_negative(),
id: UnitId::TracePos(rup.trace.len()),
});
rup.trace_edges.push(rup.trace.len() as LitIdx);
rup.trace.push(TraceItem {
id,
edges: 0..0,
unused: true,
});
}
UnitId::TracePos(pos) => {
rup.trace_edges.push(pos as LitIdx);
}
UnitId::InClause => {}
},
None => {
unassigned_count += 1;
unassigned_lit = Some(lit);
}
}
}
let range = range_begin..rup.trace_edges.len();
match unassigned_lit {
None => {
rup.trace.push(TraceItem {
id: clause.id,
edges: range,
unused: false,
});
rup_is_unsat = true;
break 'hashes;
}
Some(lit) if unassigned_count == 1 => {
rup.trail.push((lit, clauses.unit_clauses[lit.index()]));
clauses.unit_clauses[lit.index()] = Some(UnitClause {
value: lit.is_positive(),
id: UnitId::TracePos(rup.trace.len()),
});
rup.trace.push(TraceItem {
id: clause.id,
edges: range,
unused: true,
});
}
_ => (),
}
}
}
if rup_is_unsat && !ctx.part(ProcessingP).processors.is_empty() {
for i in (0..rup.trace.len()).rev() {
if !rup.trace[i].unused {
let edges = rup.trace[i].edges.clone();
for &edge in rup.trace_edges[edges].iter() {
rup.trace[edge as usize].unused = false;
}
}
}
rup.trace_ids.clear();
rup.trace_ids.extend(rup.trace.iter().map(|trace| trace.id));
}
// Undo temporary assignments
for (lit, value) in rup.trail.drain(..).rev() {
clauses.unit_clauses[lit.index()] = value;
}
if rup_is_unsat {
Ok(())
} else {
Err(CheckerError::check_failed(
ctx.part(CheckerStateP).step,
format!("AT check failed for {:?}", lits),
))
}
}
|
