[passes] linearization of merge (untested)

src/main.ml

@@ -40,7 +40,8 @@ let exec_passes ast verbose debug passes f =
 let _ =
   (** Usage and argument parsing. *)
   let default_passes =
-      ["linearization_reset"; "automata_translation"; "remove_if";
+    ["linearization_reset"; "automata_translation"; "remove_if";
+      "linearization_merge";
       "linearization_pre"; "linearization_tuples"; "linearization_app";
       "ensure_assign_val";
       "equations_ordering";
@@ -82,6 +83,7 @@ let _ =
   List.iter (fun (s, k) -> Hashtbl.add passes_table s k)
     [
       ("remove_if", Passes.pass_if_removal);
+      ("linearization_merge", Passes.pass_merge_lin);
       ("linearization_tuples", Passes.pass_linearization_tuples);
       ("linearization_app", Passes.pass_linearization_app);
       ("linearization_pre", Passes.pass_linearization_pre);

src/passes.ml

@@ -6,6 +6,89 @@ open Utils
 
 
 
+let pass_merge_lin verbose debug =
+  let varname_prefix = "_mergelin" in
+  let count = ref 0 in
+  let rec aux_expr vars expr toplevel =
+    match expr with
+    | EVar _ | EConst _ -> [], vars, expr
+    | EMonOp (t, op, e) ->
+      let eqs, vars, e = aux_expr vars e false in
+      eqs, vars, EMonOp (t, op, e)
+    | EBinOp (t, op, e, e') ->
+      let eqs, vars, e = aux_expr vars e false in
+      let eqs', vars, e' = aux_expr vars e' false in
+      eqs'@eqs, vars, EBinOp (t, op, e, e')
+    | EComp (t, op, e, e') ->
+      let eqs, vars, e = aux_expr vars e false in
+      let eqs', vars, e' = aux_expr vars e' false in
+      eqs'@eqs, vars, EComp (t, op, e, e')
+    | EReset (t, e, e') ->
+      let eqs, vars, e = aux_expr vars e false in
+      let eqs', vars, e' = aux_expr vars e' false in
+      eqs'@eqs, vars, EReset (t, e, e')
+    | ETuple (t, l) ->
+      let eqs, vars, l = List.fold_right
+        (fun e (eqs, vars, l) ->
+          let eqs', vars, e = aux_expr vars e false in
+          eqs' @ eqs, vars, (e :: l))
+        l ([], vars, []) in
+      eqs, vars, ETuple (t, l)
+    | EApp (t, n, e) ->
+      let eqs, vars, e = aux_expr vars e false in
+      eqs, vars, EApp (t, n, e)
+    | ETriOp (_, TOp_if, _, _, _) ->
+        raise (PassExn "There should no longer be any condition.")
+    | EWhen (t, e, e') ->
+      let eqs, vars, e = aux_expr vars e false in
+      let eqs', vars, e' = aux_expr vars e' false in
+      eqs @ eqs', vars, EWhen (t, e, e')
+    | ETriOp (t, TOp_merge, c, e, e') ->
+      begin
+        if toplevel
+          then
+            begin
+            let eqs, vars, c = aux_expr vars c false in
+            let eqs', vars, e = aux_expr vars e false in
+            let eqs'', vars, e' = aux_expr vars e' false in
+            eqs@eqs'@eqs'', vars, ETriOp (t, TOp_merge, c, e, e')
+            end
+          else
+            begin
+            if List.length t = 1
+              then
+                let newvar = Format.sprintf "%s%d" varname_prefix !count in
+                let newvar =
+                  match List.hd t with
+                  | TInt -> IVar newvar
+                  | TBool -> BVar newvar
+                  | TReal -> RVar newvar
+                  in
+                let () = incr count in
+                let vars = (t @ (fst vars), newvar :: (snd vars)) in
+                let eqs, vars, c = aux_expr vars c false in
+                let eqs', vars, e = aux_expr vars e false in
+                let eqs'', vars, e' = aux_expr vars e' false in
+                ((t, [newvar]), ETriOp (t, TOp_merge, c, e, e')) :: eqs @ eqs' @ eqs'', vars, EVar (t, newvar)
+              else
+                raise (PassExn "Merges should only happened on unary expressions.")
+            end
+      end
+  in
+  let aux_merge_lin node =
+    let eqs, vars =
+      List.fold_left
+        (fun (eqs, vars) (patt, expr) ->
+          let eqs', vars, expr = aux_expr vars expr true in
+          (patt, expr) :: eqs' @ eqs, vars)
+        ([], node.n_local_vars) node.n_equations
+      in
+    Some { node with n_local_vars = vars; n_equations = eqs }
+  in
+  node_pass aux_merge_lin
+
+
+
 (** [pass_if_removal] replaces the `if` construct with `when` and `merge` ones.
   *
   *     [x1, ..., xn = if c then e_l else e_r;]