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refactor(sat): cleaner store for delayed actions

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handles clauses to add, propagations, and decisions. The latter ones are
cleared on backtrack (but not clauses).
This commit is contained in:
Simon Cruanes 2022-01-11 16:50:59 -05:00
parent 999e83f91c
commit 803b40bccf
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1 changed files with 142 additions and 116 deletions
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258
src/sat/Solver.ml
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@ -620,17 +620,91 @@ module Make(Plugin : PLUGIN)
number of clauses by default *)
let learntsize_factor = 1. /. 3.
type action =
| Propagate_lit of {
p: atom;
lvl: int;
reason: reason;
}
| Add_clause_learnt of clause
| Add_clause_pool of {
c: clause;
pool: clause_pool;
}
(** Actions from theories and user, but to be done in specific points
of the solving loops. *)
module Delayed_actions : sig
type t
val create: unit -> t
val is_empty : t -> bool
val clear : t -> unit
val clear_on_backtrack : t -> unit
val add_clause_learnt : t -> clause -> unit
val add_clause_pool : t -> clause -> clause_pool -> unit
val propagate_atom : t -> atom -> lvl:int -> clause lazy_t -> unit
val add_decision : t -> atom -> unit
val iter :
decision:(atom -> unit) ->
propagate:(atom -> lvl:int -> clause lazy_t -> unit) ->
add_clause_learnt:(clause -> unit) ->
add_clause_pool:(clause -> clause_pool -> unit) ->
t -> unit
end = struct
type t = {
clauses_to_add_learnt : CVec.t;
(* Clauses either assumed or pushed by the theory, waiting to be added. *)
clauses_to_add_in_pool : (clause * clause_pool) Vec.t;
(* clauses to add into a pool *)
mutable prop_level: int;
propagate : (atom * int * clause lazy_t) Vec.t;
decisions: atom Vec.t;
}
let create() : t = {
clauses_to_add_learnt=CVec.create();
clauses_to_add_in_pool=Vec.create();
prop_level= -1;
propagate=Vec.create();
decisions=Vec.create();
}
let clear self =
let {clauses_to_add_learnt; clauses_to_add_in_pool; prop_level=_;
propagate; decisions} = self in
Vec.clear clauses_to_add_in_pool;
CVec.clear clauses_to_add_learnt;
Vec.clear propagate;
Vec.clear decisions
let clear_on_backtrack self =
let {clauses_to_add_learnt=_; clauses_to_add_in_pool=_;
propagate; prop_level=_; decisions} = self in
Vec.clear propagate;
Vec.clear decisions
let is_empty self =
let {clauses_to_add_learnt; clauses_to_add_in_pool;
prop_level=_; propagate; decisions} = self in
Vec.is_empty clauses_to_add_in_pool &&
CVec.is_empty clauses_to_add_learnt &&
Vec.is_empty decisions &&
Vec.is_empty propagate
let add_clause_pool (self:t) c pool = Vec.push self.clauses_to_add_in_pool (c,pool)
let add_clause_learnt (self:t) c = CVec.push self.clauses_to_add_learnt c
let propagate_atom self p ~lvl c =
if not (Vec.is_empty self.propagate) && lvl < self.prop_level then (
Vec.clear self.propagate; (* will be immediately backtracked *)
);
if lvl <= self.prop_level then (
self.prop_level <- lvl;
Vec.push self.propagate (p,lvl,c)
)
let add_decision self p = Vec.push self.decisions p
let iter ~decision ~propagate ~add_clause_learnt ~add_clause_pool self : unit =
let {clauses_to_add_learnt; clauses_to_add_in_pool;
prop_level=_; propagate=prop; decisions} = self in
Vec.iter (fun (c,p) -> add_clause_pool c p) clauses_to_add_in_pool;
CVec.iter ~f:add_clause_learnt clauses_to_add_learnt;
Vec.iter decision decisions;
Vec.iter (fun (p,lvl,c) -> propagate p ~lvl c) prop;
clear self;
()
end
(* Singleton type containing the current state *)
type t = {
@ -656,12 +730,6 @@ module Make(Plugin : PLUGIN)
(* learnt clauses (tautologies true at any time, whatever the user level).
GC'd regularly. *)
clauses_to_add_learnt : CVec.t;
(* Clauses either assumed or pushed by the theory, waiting to be added. *)
clauses_to_add_in_pool : (clause * clause_pool) Vec.t;
(* clauses to add into a pool *)
clauses_dead : CVec.t;
(* dead clauses, to be removed at next GC.
invariant: all satisfy [Clause.dead store c]. *)
@ -669,6 +737,8 @@ module Make(Plugin : PLUGIN)
clause_pools : clause_pool Vec.t;
(* custom clause pools *)
delayed_actions: Delayed_actions.t;
mutable unsat_at_0: clause option;
(* conflict at level 0, if any *)
@ -753,10 +823,8 @@ module Make(Plugin : PLUGIN)
make_gc_clause_pool_
~descr:(fun () -> "cp.learnt-clauses")
~max_size:max_clauses_learnt ();
clauses_to_add_learnt = CVec.create ();
clauses_to_add_in_pool = Vec.create();
delayed_actions=Delayed_actions.create();
clauses_dead = CVec.create();
clause_pools = Vec.create();
to_clear=Vec.create();
@ -1122,6 +1190,7 @@ module Make(Plugin : PLUGIN)
AVec.shrink self.trail !head;
VecSmallInt.shrink self.var_levels lvl;
Plugin.pop_levels self.th n;
Delayed_actions.clear_on_backtrack self.delayed_actions;
(* TODO: for scoped clause pools, backtrack them *)
self.next_decisions <- [];
);
@ -1619,25 +1688,6 @@ module Make(Plugin : PLUGIN)
Log.debugf 5
(fun k->k "(@[sat.add-clause@ :ignore-trivial @[%a@]@])" (Clause.debug store) init)
let[@inline never] flush_clauses_ (self:t) : unit =
while not @@ CVec.is_empty self.clauses_to_add_learnt do
let c = CVec.pop self.clauses_to_add_learnt in
add_clause_ ~pool:self.clauses_learnt self c
done;
while not @@ Vec.is_empty self.clauses_to_add_in_pool do
let c, pool = Vec.pop_exn self.clauses_to_add_in_pool in
add_clause_ ~pool self c
done;
()
let[@inline] has_no_new_clauses (self:t) : bool =
CVec.is_empty self.clauses_to_add_learnt && Vec.is_empty self.clauses_to_add_in_pool
let[@inline] flush_clauses self =
if not (has_no_new_clauses self) then (
flush_clauses_ self
)
type watch_res =
| Watch_kept
| Watch_removed
@ -1726,7 +1776,7 @@ module Make(Plugin : PLUGIN)
let c = Clause.make_l self.store ~removable atoms p in
Log.debugf 5 (fun k->k "(@[sat.th.add-clause@ %a@])" (Clause.debug self.store) c);
(* will be added later, even if we backtrack *)
CVec.push self.clauses_to_add_learnt c
Delayed_actions.add_clause_learnt self.delayed_actions c
let acts_add_clause_in_pool self ~pool (l:lit list) (p:proof_step): unit =
let atoms = List.rev_map (make_atom_ self) l in
@ -1737,44 +1787,15 @@ module Make(Plugin : PLUGIN)
(Clause.debug self.store) c
(cp_descr_ pool));
(* will be added later, even if we backtrack *)
Vec.push self.clauses_to_add_in_pool (c, pool)
Delayed_actions.add_clause_pool self.delayed_actions c pool
module Th_action = struct
type t =
| Add_decision of atom
| Propagate_atom of {
p: atom;
lvl: int;
reason: clause lazy_t;
}
end
module Th_action_queue : sig
type t
val create: unit -> t
val is_empty : t -> bool
val clear : t -> unit
val pop : t -> Th_action.t
val add : t -> Th_action.t -> unit
end = struct
type t = {
st: Th_action.t Vec.t;
} [@@unboxed]
let create() : t = { st=Vec.create() }
let clear self = Vec.clear self.st
let is_empty self = Vec.is_empty self.st
let pop self = Vec.pop_exn self.st
let add (self:t) (act:Th_action.t) = Vec.push self.st act
end
let acts_add_decision_lit (self:t) (q:Th_action_queue.t) (f:lit) (sign:bool) : unit =
let acts_add_decision_lit (self:t) (f:lit) (sign:bool) : unit =
let store = self.store in
let a = make_atom_ self f in
let a = if sign then a else Atom.neg a in
if not (Atom.has_value store a) then (
Log.debugf 10 (fun k->k "(@[sat.th.add-decision-lit@ %a@])" (Atom.debug store) a);
Th_action_queue.add q (Th_action.Add_decision a)
Delayed_actions.add_decision self.delayed_actions a;
)
let acts_raise self (l:lit list) (p:proof_step) : 'a =
@ -1798,7 +1819,7 @@ module Make(Plugin : PLUGIN)
(Atom.debug store) (Atom.neg a)
| exception Not_found -> ()
let acts_propagate (self:t) (q:Th_action_queue.t) f (expl:(_,proof_step) Solver_intf.reason) =
let acts_propagate (self:t) f (expl:(_,proof_step) Solver_intf.reason) =
let store = self.store in
match expl with
| Solver_intf.Consequence mk_expl ->
@ -1835,27 +1856,37 @@ module Make(Plugin : PLUGIN)
(* delay creating the actual clause. *)
lazy (Clause.make_l store ~removable:true (p::guard) proof), level
) in
let act = Th_action.Propagate_atom {p; lvl=level; reason=c} in
Th_action_queue.add q act
Delayed_actions.propagate_atom self.delayed_actions p ~lvl:level c
)
let perform_th_actions_ (self:solver) (acts:Th_action_queue.t) =
while not (Th_action_queue.is_empty acts) do
let act = Th_action_queue.pop acts in
match act with
| Th_action.Add_decision a ->
self.next_decisions <- a :: self.next_decisions
| Th_action.Propagate_atom {p; lvl; reason=c} ->
if Atom.is_true self.store p then ()
else if Atom.is_false self.store p then (
raise_notrace (Th_conflict (Lazy.force c))
) else (
(* if we backjump, rest of propagations are moot *)
if lvl < decision_level self then Th_action_queue.clear acts;
Stat.incr self.n_propagations;
enqueue_bool self p ~level:lvl (Bcp_lazy c)
)
done
let[@inline never] perform_delayed_actions_ (self:t) : unit =
let add_clause_learnt c =
add_clause_ ~pool:self.clauses_learnt self c
and add_clause_pool c pool =
add_clause_ ~pool self c
and decision a =
self.next_decisions <- a :: self.next_decisions
and propagate p ~lvl c =
if Atom.is_true self.store p then ()
else if Atom.is_false self.store p then (
raise_notrace (Th_conflict (Lazy.force c))
) else (
Stat.incr self.n_propagations;
enqueue_bool self p ~level:lvl (Bcp_lazy c)
)
in
Delayed_actions.iter self.delayed_actions
~add_clause_learnt
~add_clause_pool ~propagate ~decision;
()
let[@inline] has_no_delayed_actions (self:t) : bool =
Delayed_actions.is_empty self.delayed_actions
let[@inline] perform_delayed_actions self =
if not (has_no_delayed_actions self) then (
perform_delayed_actions_ self
)
let[@specialise] acts_iter self ~full head f : unit =
for i = (if full then 0 else head) to AVec.size self.trail-1 do
@ -1875,7 +1906,7 @@ module Make(Plugin : PLUGIN)
let[@inline] acts_add_lit self ?default_pol f : unit =
ignore (make_atom_ ?default_pol self f : atom)
let[@inline] current_slice st q : _ Solver_intf.acts =
let[@inline] current_slice st : _ Solver_intf.acts =
let module M = struct
type nonrec proof = proof
type nonrec proof_step = proof_step
@ -1887,14 +1918,14 @@ module Make(Plugin : PLUGIN)
let add_lit=acts_add_lit st
let add_clause = acts_add_clause st
let add_clause_in_pool = acts_add_clause_in_pool st
let propagate = acts_propagate st q
let propagate = acts_propagate st
let raise_conflict c pr=acts_raise st c pr
let add_decision_lit=acts_add_decision_lit st q
let add_decision_lit=acts_add_decision_lit st
end in
(module M)
(* full slice, for [if_sat] final check *)
let[@inline] full_slice st q : _ Solver_intf.acts =
let[@inline] full_slice st : _ Solver_intf.acts =
let module M = struct
type nonrec proof = proof
type nonrec proof_step = proof_step
@ -1906,9 +1937,9 @@ module Make(Plugin : PLUGIN)
let add_lit=acts_add_lit st
let add_clause = acts_add_clause st
let add_clause_in_pool = acts_add_clause_in_pool st
let propagate = acts_propagate st q
let propagate = acts_propagate st
let raise_conflict c pr=acts_raise st c pr
let add_decision_lit=acts_add_decision_lit st q
let add_decision_lit=acts_add_decision_lit st
end in
(module M)
@ -1928,13 +1959,11 @@ module Make(Plugin : PLUGIN)
if self.th_head = self.elt_head then (
None (* fixpoint/no propagation *)
) else (
let q = Th_action_queue.create() in
let slice = current_slice self q in
let slice = current_slice self in
self.th_head <- self.elt_head; (* catch up *)
match Plugin.partial_check self.th slice with
| () ->
perform_th_actions_ self q;
flush_clauses self;
perform_delayed_actions self;
propagate self
| exception Th_conflict c ->
check_is_conflict_ self c;
@ -1945,8 +1974,8 @@ module Make(Plugin : PLUGIN)
(* fixpoint between boolean propagation and theory propagation
@return a conflict clause, if any *)
and propagate (st:t) : clause option =
(* First, treat the stack of lemmas added by the theory, if any *)
flush_clauses st;
(* First, treat the stack of lemmas/actions added by the theory, if any *)
perform_delayed_actions st;
(* Now, check that the situation is sane *)
assert (st.elt_head <= AVec.size st.trail);
if st.elt_head = AVec.size st.trail then (
@ -2222,7 +2251,7 @@ module Make(Plugin : PLUGIN)
Log.debugf 5 (fun k->k "(@[sat.solve :assms %d@])" (AVec.size self.assumptions));
check_unsat_ self;
try
flush_clauses self; (* add initial clauses *)
perform_delayed_actions self; (* add initial clauses *)
let max_conflicts = ref (float_of_int restart_first) in
let max_learnt = ref ((float_of_int (nb_clauses self)) *. learntsize_factor) in
while true do
@ -2236,21 +2265,18 @@ module Make(Plugin : PLUGIN)
max_learnt := !max_learnt *. learntsize_inc
| E_sat ->
assert (self.elt_head = AVec.size self.trail &&
has_no_new_clauses self &&
has_no_delayed_actions self &&
self.next_decisions=[]);
let q = Th_action_queue.create() in
begin match Plugin.final_check self.th (full_slice self q) with
begin match Plugin.final_check self.th (full_slice self) with
| () ->
if self.elt_head = AVec.size self.trail &&
has_no_new_clauses self &&
Th_action_queue.is_empty q &&
has_no_delayed_actions self &&
self.next_decisions = []
then (
raise_notrace E_sat
);
(* otherwise, keep on *)
perform_th_actions_ self q;
flush_clauses self;
perform_delayed_actions self;
| exception Th_conflict c ->
check_is_conflict_ self c;
Clause.iter self.store c
@ -2259,8 +2285,8 @@ module Make(Plugin : PLUGIN)
(Clause.debug self.store) c);
Stat.incr self.n_conflicts;
(match self.on_conflict with Some f -> f self c | None -> ());
CVec.push self.clauses_to_add_learnt c;
flush_clauses self;
Delayed_actions.add_clause_learnt self.delayed_actions c;
perform_delayed_actions self;
end;
end
done
@ -2274,7 +2300,7 @@ module Make(Plugin : PLUGIN)
let c = Clause.make_a self.store ~removable:false atoms proof in
Log.debugf 10 (fun k -> k "(@[sat.assume-clause@ @[<hov 2>%a@]@])"
(Clause.debug self.store) c);
CVec.push self.clauses_to_add_learnt c)
Delayed_actions.add_clause_learnt self.delayed_actions c)
cnf
let[@inline] theory st = st.th
@ -2523,7 +2549,7 @@ module Make(Plugin : PLUGIN)
with_local_assumptions_ self assumptions @@ fun () ->
try
check_unsat_ self;
flush_clauses self; (* add initial clauses *)
perform_delayed_actions self; (* add initial clauses *)
propagate_under_assumptions self
with
| E_unsat us ->