wip: new attempt at theory combination

src/base/Sidekick_base.ml

@@ -33,7 +33,7 @@ module LRA_term = LRA_term
 module Th_data = Th_data
 module Th_bool = Th_bool
 module Th_lra = Th_lra
-module Th_uf = Th_uf
+module Th_ty_unin = Th_ty_unin
 
 let k_th_bool_config = Th_bool.k_config
 let th_bool = Th_bool.theory
@@ -41,4 +41,4 @@ let th_bool_dyn : Solver.theory = Th_bool.theory_dyn
 let th_bool_static : Solver.theory = Th_bool.theory_static
 let th_data : Solver.theory = Th_data.theory
 let th_lra : Solver.theory = Th_lra.theory
-let th_uf : Solver.theory = Th_uf.theory
+let th_ty_unin : Solver.theory = Th_ty_unin.theory

src/base/dune

@@ -4,5 +4,6 @@
  (synopsis "Base term definitions for the standalone SMT solver and library")
  (libraries containers iter sidekick.core sidekick.util sidekick.smt-solver
    sidekick.cc sidekick.quip sidekick.th-lra sidekick.th-bool-static
-   sidekick.th-bool-dyn sidekick.th-data sidekick.zarith zarith)
+   sidekick.th-ty-unin sidekick.th-bool-dyn sidekick.th-data sidekick.zarith
+   zarith)
  (flags :standard -w +32 -open Sidekick_util))

src/main/main.ml

@@ -177,7 +177,7 @@ let main_smt ~config () : _ result =
       Log.debugf 1 (fun k ->
           k "(@[main.th-bool.pick@ %S@])"
             (Sidekick_smt_solver.Theory.name th_bool));
-      [ th_bool; Process.th_uf; Process.th_data; Process.th_lra ]
+      [ th_bool; Process.th_ty_unin; Process.th_data; Process.th_lra ]
     in
     Process.Solver.create_default ~proof ~theories tst
   in

src/smt/solver.ml

@@ -168,6 +168,7 @@ let assert_terms self c =
   add_clause_l self c pr_c
 
 let assert_term self t = assert_terms self [ t ]
+let add_ty (self : t) ty = SI.add_ty self.si ~ty
 
 let solve ?(on_exit = []) ?(check = true) ?(on_progress = fun _ -> ())
     ?(should_stop = fun _ _ -> false) ~assumptions (self : t) : res =

src/smt/solver.mli

@@ -111,6 +111,8 @@ val assert_term : t -> term -> unit
 (** Helper that turns the term into an atom, before adding the result
       to the solver as a unit clause assertion *)
 
+val add_ty : t -> ty -> unit
+
 (** Result of solving for the current set of clauses *)
 type res =
   | Sat of Model.t  (** Satisfiable *)

src/smt/solver_internal.ml

@@ -38,7 +38,9 @@ type t = {
   cc: CC.t;  (** congruence closure *)
   proof: proof_trace;  (** proof logger *)
   registry: Registry.t;
+  seen_types: Term.Weak_set.t;  (** types we've seen so far *)
   on_progress: (unit, unit) Event.Emitter.t;
+  on_new_ty: (ty, unit) Event.Emitter.t;
   th_comb: Th_combination.t;
   mutable on_partial_check: (t -> theory_actions -> lit Iter.t -> unit) list;
   mutable on_final_check: (t -> theory_actions -> lit Iter.t -> unit) list;
@@ -82,7 +84,9 @@ let[@inline] has_delayed_actions self =
   not (Queue.is_empty self.delayed_actions)
 
 let on_preprocess self f = self.preprocess <- f :: self.preprocess
-let claim_term self ~th_id t = Th_combination.claim_term self.th_comb ~th_id t
+
+let claim_sort self ~th_id ~ty =
+  Th_combination.claim_sort self.th_comb ~th_id ~ty
 
 let on_model ?ask ?complete self =
   Option.iter (fun f -> self.model_ask <- f :: self.model_ask) ask;
@@ -135,6 +139,14 @@ let preprocess_term_ (self : t) (t0 : term) : unit =
     if not (Term.Tbl.mem self.preprocessed t) then (
       Term.Tbl.add self.preprocessed t ();
 
+      (* see if this is a new type *)
+      let ty = Term.ty t in
+      if not (Term.Weak_set.mem self.seen_types ty) then (
+        Log.debugf 5 (fun k -> k "(@[solver.seen-new-type@ %a@])" Term.pp ty);
+        Term.Weak_set.add self.seen_types ty;
+        Event.Emitter.emit self.on_new_ty ty
+      );
+
       (* process sub-terms first *)
       Term.iter_shallow t ~f:(fun _inb u -> preproc_rec_ u);
 
@@ -166,6 +178,7 @@ let preprocess_term_ (self : t) (t0 : term) : unit =
 let simplify_and_preproc_lit (self : t) (lit : Lit.t) : Lit.t * step_id option =
   let t = Lit.term lit in
   let sign = Lit.sign lit in
+
   let u, pr =
     match simplify_t self t with
     | None -> t, None
@@ -274,6 +287,12 @@ let[@inline] add_clause_permanent self _acts c (proof : step_id) : unit =
 
 let[@inline] mk_lit self ?sign t : lit = Lit.atom ?sign self.tst t
 
+let add_ty self ~ty : unit =
+  if not (Term.Weak_set.mem self.seen_types ty) then (
+    Term.Weak_set.add self.seen_types ty;
+    Event.Emitter.emit self.on_new_ty ty
+  )
+
 let[@inline] add_lit self _acts ?default_pol lit =
   delayed_add_lit self ?default_pol lit
 
@@ -288,6 +307,7 @@ let on_partial_check self f =
   self.on_partial_check <- f :: self.on_partial_check
 
 let on_progress self = Event.of_emitter self.on_progress
+let on_new_ty self = Event.of_emitter self.on_new_ty
 let on_cc_new_term self f = Event.on (CC.on_new_term (cc self)) ~f
 let on_cc_pre_merge self f = Event.on (CC.on_pre_merge (cc self)) ~f
 let on_cc_post_merge self f = Event.on (CC.on_post_merge (cc self)) ~f
@@ -334,6 +354,9 @@ let mk_model_ (self : t) (lits : lit Iter.t) : Model.t =
 
   let model = Model_builder.create tst in
 
+  Model_builder.add model (Term.true_ tst) (Term.true_ tst);
+  Model_builder.add model (Term.false_ tst) (Term.false_ tst);
+
   (* first, add all literals to the model using the given propositional model
      induced by the trail [lits]. *)
   lits (fun lit ->
@@ -363,6 +386,9 @@ let mk_model_ (self : t) (lits : lit Iter.t) : Model.t =
   let rec compute_fixpoint () =
     match MB.pop_required model with
     | None -> ()
+    | Some t when Term.is_pi (Term.ty t) ->
+      (* TODO: when we support lambdas? *)
+      ()
     | Some t ->
       (* compute a value for [t] *)
       Log.debugf 5 (fun k ->
@@ -371,11 +397,9 @@ let mk_model_ (self : t) (lits : lit Iter.t) : Model.t =
       (* try each model hook *)
       let rec try_hooks_ = function
         | [] ->
-          let c = MB.gensym model ~pre:"@c" ~ty:(Term.ty t) in
-          Log.debugf 10 (fun k ->
-              k "(@[model.fixpoint.pick-default-val@ %a@ :for %a@])" Term.pp c
-                Term.pp t);
-          MB.add model t c
+          (* should not happen *)
+          Error.errorf "cannot build a value for term@ `%a`@ of type `%a`"
+            Term.pp t Term.pp (Term.ty t)
         | h :: hooks ->
           (match h self model t with
           | None -> try_hooks_ hooks
@@ -392,6 +416,32 @@ let mk_model_ (self : t) (lits : lit Iter.t) : Model.t =
   compute_fixpoint ();
   MB.to_model model
 
+(* theory combination: find terms occurring as foreign variables in
+   other terms *)
+let theory_comb_register_new_term (self : t) (t : term) : unit =
+  Log.debugf 50 (fun k -> k "(@[solver.th-comb-register@ %a@])" Term.pp t);
+  match Th_combination.claimed_by self.th_comb ~ty:(Term.ty t) with
+  | None -> ()
+  | Some theory_for_t ->
+    let args =
+      let _f, args = Term.unfold_app t in
+      match Term.view _f, args, Term.view t with
+      | Term.E_const { Const.c_ops = (module OP); c_view; _ }, _, _
+        when OP.opaque_to_cc c_view ->
+        []
+      | _, [], Term.E_app_fold { args; _ } -> args
+      | _ -> args
+    in
+    List.iter
+      (fun arg ->
+        match Th_combination.claimed_by self.th_comb ~ty:(Term.ty arg) with
+        | Some theory_for_arg
+          when not (Theory_id.equal theory_for_t theory_for_arg) ->
+          (* [arg] is foreign *)
+          Th_combination.add_term_needing_combination self.th_comb arg
+        | _ -> ())
+      args
+
 (* call congruence closure, perform the actions it scheduled *)
 let check_cc_with_acts_ (self : t) (acts : theory_actions) =
   let (module A) = acts in
@@ -529,8 +579,10 @@ let create (module A : ARG) ~stat ~proof (tst : Term.store) () : t =
       stat;
       simp = Simplify.create tst ~proof;
       last_model = None;
+      seen_types = Term.Weak_set.create 8;
       th_comb = Th_combination.create ~stat tst;
       on_progress = Event.Emitter.create ();
+      on_new_ty = Event.Emitter.create ();
       preprocess = [];
       model_ask = [];
       model_complete = [];
@@ -547,4 +599,8 @@ let create (module A : ARG) ~stat ~proof (tst : Term.store) () : t =
       complete = true;
     }
   in
+  (* observe new terms in the CC *)
+  on_cc_new_term self (fun (_, _, t) ->
+      theory_comb_register_new_term self t;
+      []);
   self

src/smt/solver_internal.mli

@@ -98,9 +98,10 @@ val preprocess_clause_array : t -> lit array -> step_id -> lit array * step_id
 val simplify_and_preproc_lit : t -> lit -> lit * step_id option
 (** Simplify literal then preprocess it *)
 
-val claim_term : t -> th_id:Theory_id.t -> term -> unit
-(** Claim a term, for a theory that might decide or merge it with another
-    term. This is useful for theory combination. *)
+val claim_sort : t -> th_id:Theory_id.t -> ty:ty -> unit
+(** Claim a sort, to be called by the theory with id [th_id] which is
+    responsible for this sort in models. This is useful for theory combination.
+    *)
 
 (** {3 hooks for the theory} *)
 
@@ -130,6 +131,9 @@ val add_clause_permanent : t -> theory_actions -> lit list -> step_id -> unit
 (** Add toplevel clause to the SAT solver. This clause will
       not be backtracked. *)
 
+val add_ty : t -> ty:term -> unit
+(** Declare a sort for the SMT solver *)
+
 val mk_lit : t -> ?sign:bool -> term -> lit
 (** Create a literal. This automatically preprocesses the term. *)
 
@@ -204,6 +208,9 @@ val on_cc_propagate :
   unit
 (** Callback called on every CC propagation *)
 
+val on_new_ty : t -> (ty, unit) Event.t
+(** Add a callback for when new types are added via {!add_ty} *)
+
 val on_partial_check : t -> (t -> theory_actions -> lit Iter.t -> unit) -> unit
 (** Register callbacked to be called with the slice of literals
       newly added on the trail.

src/smtlib/Process.ml

@@ -332,7 +332,9 @@ let process_stmt ?gc ?restarts ?(pp_cnf = false) ?proof_file ?pp_model
       Fmt.printf "(@[%a@])@." (Util.pp_list pp_pair) l
     | _ -> Error.errorf "cannot access model");
     E.return ()
-  | Statement.Stmt_data _ -> E.return ()
+  | Statement.Stmt_data ds ->
+    List.iter (fun d -> Solver.add_ty solver (Data_ty.data_as_ty d)) ds;
+    E.return ()
   | Statement.Stmt_define _ -> Error.errorf "cannot deal with definitions yet"
 
 open Sidekick_base
@@ -342,4 +344,4 @@ let th_bool_dyn : Solver.theory = Th_bool.theory_dyn
 let th_bool_static : Solver.theory = Th_bool.theory_static
 let th_data : Solver.theory = Th_data.theory
 let th_lra : Solver.theory = Th_lra.theory
-let th_uf = Th_uf.theory
+let th_ty_unin = Th_ty_unin.theory

src/smtlib/Process.mli

@@ -8,7 +8,7 @@ val th_bool_static : Solver.theory
 val th_bool : Config.t -> Solver.theory
 val th_data : Solver.theory
 val th_lra : Solver.theory
-val th_uf : Solver.theory
+val th_ty_unin : Solver.theory
 
 type 'a or_error = ('a, string) CCResult.t
 

src/th-data/Sidekick_th_data.ml

@@ -465,7 +465,8 @@ end = struct
     | T_cstor _ | T_other _ -> []
 
   let on_is_subterm (self : t) (si : SI.t) (_cc, _repr, t) : _ list =
-    if is_data_ty (Term.ty t) then SI.claim_term si ~th_id:self.th_id t;
+    if is_data_ty (Term.ty t) then
+      SI.claim_sort si ~th_id:self.th_id ~ty:(Term.ty t);
     []
 
   let cstors_of_ty (ty : ty) : A.Cstor.t list =
@@ -788,6 +789,9 @@ end = struct
         Some (c, args))
     | None -> None
 
+  (* TODO: event/function to declare new datatypes, so we can claim them
+     early *)
+
   let create_and_setup ~id:th_id (solver : SI.t) : t =
     let self =
       {

src/th-lra/sidekick_th_lra.ml

@@ -298,15 +298,6 @@ module Make (A : ARG) = (* : S with module A = A *) struct
 
         proxy, A.Q.one)
 
-  (* look for subterms of type Real, for they will need theory combination *)
-  let on_subterm (self : state) (si : SI.t) (t : Term.t) : unit =
-    Log.debugf 50 (fun k -> k "(@[lra.cc-on-subterm@ %a@])" Term.pp_debug t);
-    match A.view_as_lra t with
-    | LRA_other _ when not (A.has_ty_real t) -> ()
-    | LRA_pred _ | LRA_const _ -> ()
-    | LRA_op _ | LRA_other _ | LRA_mult _ ->
-      SI.claim_term si ~th_id:self.th_id t
-
   (* preprocess linear expressions away *)
   let preproc_lra (self : state) si (module PA : SI.PREPROCESS_ACTS)
       (t : Term.t) : unit =
@@ -314,11 +305,10 @@ module Make (A : ARG) = (* : S with module A = A *) struct
     let tst = SI.tst si in
 
     (* tell the CC this term exists *)
-    let declare_term_to_cc ~sub t =
+    let declare_term_to_cc ~sub:_ t =
       Log.debugf 50 (fun k ->
           k "(@[lra.declare-term-to-cc@ %a@])" Term.pp_debug t);
-      ignore (CC.add_term (SI.cc si) t : E_node.t);
-      if sub then on_subterm self si t
+      ignore (CC.add_term (SI.cc si) t : E_node.t)
     in
 
     match A.view_as_lra t with
@@ -672,6 +662,7 @@ module Make (A : ARG) = (* : S with module A = A *) struct
 
   (* help generating model *)
   let model_ask_ (self : state) _si _model (t : Term.t) : _ option =
+    let res =
       match self.last_res with
       | Some (SimpSolver.Sat m) ->
         Log.debugf 50 (fun k -> k "(@[lra.model-ask@ %a@])" Term.pp_debug t);
@@ -680,6 +671,16 @@ module Make (A : ARG) = (* : S with module A = A *) struct
         | _ -> SimpSolver.V_map.get t m)
         |> Option.map (fun t -> t_const self t, [])
       | _ -> None
+    in
+    match res with
+    | Some _ -> res
+    | None when A.has_ty_real t ->
+      (* last resort: return 0 *)
+      (* NOTE: this should go away maybe? no term should escape the LRA model… *)
+      Log.debugf 0 (fun k -> k "MODEL TY REAL DEFAULT %a" Term.pp t);
+      let zero = A.mk_lra self.tst (LRA_const A.Q.zero) in
+      Some (zero, [])
+    | None -> None
 
   (* help generating model *)
   let model_complete_ (self : state) _si ~add : unit =
@@ -710,9 +711,7 @@ module Make (A : ARG) = (* : S with module A = A *) struct
     SI.on_final_check si (final_check_ st);
     (* SI.on_partial_check si (partial_check_ st); *)
     SI.on_model si ~ask:(model_ask_ st) ~complete:(model_complete_ st);
-    SI.on_cc_is_subterm si (fun (_, _, t) ->
-        on_subterm st si t;
-        []);
+    SI.claim_sort si ~th_id:id ~ty:(A.ty_real (SI.tst si));
     SI.on_cc_pre_merge si (fun (_cc, n1, n2, expl) ->
         match as_const_ (E_node.term n1), as_const_ (E_node.term n2) with
         | Some q1, Some q2 when A.Q.(q1 <> q2) ->