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feat(sat): implement phase saving in the SAT solver

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Simon Cruanes 2021-07-22 09:58:04 -04:00
parent 515a720d00
commit 62f45777a1
1 changed files with 16 additions and 12 deletions
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28
src/sat/Solver.ml
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@ -132,7 +132,7 @@ module Make(Plugin : PLUGIN)
v_weight: Vec_float.t;
v_reason: reason option Vec.t;
v_seen: Bitvec.t;
v_default_polarity: Bitvec.t;
v_last_polarity: Bitvec.t; (* phase saving *)
mutable v_count : int;
(* atoms *)
@ -159,7 +159,7 @@ module Make(Plugin : PLUGIN)
v_weight = Vec_float.create();
v_reason = Vec.create();
v_seen = Bitvec.create();
v_default_polarity = Bitvec.create();
v_last_polarity = Bitvec.create();
v_count = 0;
a_is_true=Bitvec.create();
a_form=Vec.create();
@ -195,8 +195,8 @@ module Make(Plugin : PLUGIN)
let[@inline] mark self v = Bitvec.set self.v_seen (v:var:>int) true
let[@inline] unmark self v = Bitvec.set self.v_seen (v:var:>int) false
let[@inline] marked self v = Bitvec.get self.v_seen (v:var:>int)
let[@inline] set_default_pol self v b = Bitvec.set self.v_default_polarity (v:var:>int) b
let[@inline] default_pol self v = Bitvec.get self.v_default_polarity (v:var:>int)
let[@inline] set_last_pol self v b = Bitvec.set self.v_last_polarity (v:var:>int) b
let[@inline] last_pol self v = Bitvec.get self.v_last_polarity (v:var:>int)
let[@inline] heap_idx self v = Vec.get self.v_heap_idx (v:var:>int)
let[@inline] set_heap_idx self v i = Vec.set self.v_heap_idx (v:var:>int) i
end
@ -457,7 +457,7 @@ module Make(Plugin : PLUGIN)
(* allocate new variable *)
let alloc_var_uncached_ ?default_pol:(pol=true) self (form:formula) : var =
let {v_count; v_of_form; v_level; v_heap_idx; v_weight;
v_reason; v_seen; v_default_polarity;
v_reason; v_seen; v_last_polarity;
a_is_true; a_seen; a_watched; a_form; c_store=_;
} = self in
@ -471,8 +471,8 @@ module Make(Plugin : PLUGIN)
Vec.push v_reason None;
Vec_float.push v_weight 0.;
Bitvec.ensure_size v_seen v_idx;
Bitvec.ensure_size v_default_polarity v_idx;
Bitvec.set v_default_polarity v_idx pol;
Bitvec.ensure_size v_last_polarity v_idx;
Bitvec.set v_last_polarity v_idx pol; (* initial phase *)
assert (Vec.size a_form = 2 * (v:var:>int));
Bitvec.ensure_size a_is_true (2*(v:var:>int));
@ -1286,6 +1286,7 @@ module Make(Plugin : PLUGIN)
Atom.set_is_true store a true;
Var.set_level store (Atom.var a) lvl;
Var.set_reason store (Atom.var a) (Some reason);
Var.set_last_pol store (Atom.var a) (Atom.sign a); (* save phase *)
Vec.push self.trail a;
Log.debugf 20
(fun k->k "(@[sat.enqueue[%d]@ %a@])"
@ -1968,10 +1969,11 @@ module Make(Plugin : PLUGIN)
(* Decide on a new literal, and enqueue it into the trail *)
let rec pick_branch_aux self atom : unit =
let store = self.store in
let v = Atom.var atom in
if Var.level self.store v >= 0 then (
assert (Atom.is_true self.store (Atom.pa v) ||
Atom.is_true self.store (Atom.na v));
if Var.level store v >= 0 then (
assert (Atom.is_true store (Atom.pa v) ||
Atom.is_true store (Atom.na v));
pick_branch_lit self
) else (
new_decision_level self;
@ -2002,8 +2004,10 @@ module Make(Plugin : PLUGIN)
| [] ->
begin match H.remove_min self.order with
| v ->
pick_branch_aux self
(if Var.default_pol self.store v then Atom.pa v else Atom.na v)
(* use saved polarity *)
let sign = Var.last_pol self.store v in
let a = if sign then Atom.pa v else Atom.na v in
pick_branch_aux self a
| exception Not_found -> raise_notrace E_sat
end