[sledge] Fix Exp.map and garbage_collect

Summary:
:
* Fix non termination of garbage collection
* Fix implementation of Exp.map to handle recursive Exps (vtables)

Reviewed By: jberdine

Differential Revision: D16089676

fbshipit-source-id: 337c19f18

sledge/src/llair/exp.ml

@@ -1289,6 +1289,8 @@ let size_of t =
 (** Transform *)
 
 let map e ~f =
+  let map_ : (t -> t) -> t -> t =
+   fun map_ e ->
     let map_bin mk ~f x y =
       let x' = f x in
       let y' = f y in
@@ -1309,13 +1311,16 @@ let map e ~f =
     | Splat {byt; siz} -> map_bin simp_splat ~f byt siz
     | Memory {siz; arr} -> map_bin simp_memory ~f siz arr
     | Concat {args} -> map_vector simp_concat ~f args
+    | Struct_rec {elts= args} -> Struct_rec {elts= Vector.map args ~f:map_}
     | _ -> e
+  in
+  fix map_ (fun e -> e) e
 
 let rename e sub =
   let rec rename_ e sub =
     match e with
     | Var _ -> Var.Subst.apply sub e
-    | _ -> map e ~f:(fun f -> rename_ f sub)
+    | _ -> map ~f:(fun f -> rename_ f sub) e
   in
   rename_ e sub |> check (invariant ~partial:true)
 

sledge/src/symbheap/state_domain.ml

@@ -49,7 +49,7 @@ let garbage_collect (q : t) ~wrt =
   (* only support DNF for now *)
   assert (List.is_empty q.djns) ;
   let rec all_reachable_vars previous current (q : t) =
-    if previous == current then current
+    if Var.Set.equal previous current then current
     else
       let new_set =
         List.fold ~init:current q.heap ~f:(fun current seg ->