Use set instead of toppedSet for ThreadSet

src/cdomains/concDomain.ml

@@ -1,6 +1,25 @@
 (** Domains for thread sets and their uniqueness. *)
 
-module ThreadSet = SetDomain.ToppedSet (ThreadIdDomain.Thread) (struct let topname = "All Threads" end)
+module ThreadSet = 
+struct 
+  include SetDomain.Make (ThreadIdDomain.Thread)
+
+  let is_top = mem UnknownThread
+
+  let top () = singleton UnknownThread
+
+  let merge uop cop x y =
+    match is_top x, is_top y with
+    | true, true -> uop x y
+    | false, true -> x
+    | true, false -> y
+    | false, false -> cop x y
+
+  let meet x y = merge join meet x y
+
+  let narrow x y = merge (fun x y -> widen x (join x y)) narrow x y
+
+end
 module MustThreadSet = SetDomain.Reverse(ThreadSet)
 
 module CreatedThreadSet = ThreadSet

src/cdomains/threadIdDomain.ml

@@ -279,13 +279,15 @@ struct
   let name () = "FlagConfiguredTID: " ^ if history_enabled () then H.name () else P.name ()
 end
 
-module Thread : Stateful =
+type thread =
+  | Thread of FlagConfiguredTID.t
+  | UnknownThread
+[@@deriving eq, ord, hash]
+
+module Thread : Stateful with type t = thread =
 struct
   include Printable.Std
-  type t =
-    | Thread of FlagConfiguredTID.t
-    | UnknownThread
-  [@@deriving eq, ord, hash]
+  type t = thread [@@deriving eq, ord, hash]
 
   let name () = "Thread id"
   let pretty () t =