use a mutable field instead of a reference for symbolic memory data

src/symbolic/symbolic_memory.ml

@@ -10,7 +10,7 @@ open Expr
 let page_size = Symbolic_value.const_i32 65_536l
 
 type t =
-  { data : (Int32.t, Value.int32) Hashtbl.t option ref
+  { mutable data : (Int32.t, Value.int32) Hashtbl.t option
   ; parent : t option
   ; mutable size : Value.int32
   ; chunks : (Int32.t, Value.int32) Hashtbl.t
@@ -42,11 +42,11 @@ let fill _ = assert false
 let blit _ = assert false
 
 let replace m k v =
-  match !(m.data) with
+  match m.data with
   | None ->
     let tbl = Hashtbl.create 16 in
     Hashtbl.add tbl k v;
-    m.data := Some tbl
+    m.data <- Some tbl
   | Some tbl -> Hashtbl.replace tbl k v
 
 let blit_string m str ~src ~dst ~len =
@@ -68,18 +68,16 @@ let blit_string m str ~src ~dst ~len =
   end
 
 let clone m =
-  let parent = if Option.is_none !(m.data) then m.parent else Some m in
-  { data = ref None
+  let parent = if Option.is_none m.data then m.parent else Some m in
+  { data = None
   ; parent
   ; size = m.size
   ; chunks = Hashtbl.copy m.chunks (* TODO: we can make this lazy as well *)
   }
 
 let rec load_byte { parent; data; _ } a =
   try
-    match !data with
-    | None -> raise Not_found
-    | Some data -> Hashtbl.find data a
+    match data with None -> raise Not_found | Some data -> Hashtbl.find data a
   with Not_found -> (
     match parent with
     | None -> make (Val (Num (I8 0)))

src/symbolic/symbolic_memory_concretizing.ml

@@ -4,17 +4,17 @@ module Backend = struct
   type address = Int32.t
 
   type t =
-    { data : (address, Symbolic_value.int32) Hashtbl.t option ref
+    { mutable data : (address, Symbolic_value.int32) Hashtbl.t option
     ; parent : t option
     ; chunks : (address, Symbolic_value.int32) Hashtbl.t
     }
 
-  let make () = { data = ref None; parent = None; chunks = Hashtbl.create 16 }
+  let make () = { data = None; parent = None; chunks = Hashtbl.create 16 }
 
   let clone m =
-    let parent = if Option.is_none !(m.data) then m.parent else Some m in
+    let parent = if Option.is_none m.data then m.parent else Some m in
     (* TODO: Make chunk copying lazy *)
-    { data = ref None; parent; chunks = Hashtbl.copy m.chunks }
+    { data = None; parent; chunks = Hashtbl.copy m.chunks }
 
   let address a =
     let open Symbolic_choice_without_memory in
@@ -28,7 +28,7 @@ module Backend = struct
 
   let rec load_byte { parent; data; _ } a =
     try
-      match !data with
+      match data with
       | None -> raise Not_found
       | Some data -> Hashtbl.find data a
     with Not_found -> (
@@ -97,11 +97,11 @@ module Backend = struct
     | _ -> Expr.make (Extract (v, pos + 1, pos))
 
   let replace m k v =
-    match !(m.data) with
+    match m.data with
     | None ->
       let tbl = Hashtbl.create 16 in
       Hashtbl.add tbl k v;
-      m.data := Some tbl
+      m.data <- Some tbl
     | Some tbl -> Hashtbl.replace tbl k v
 
   let storen m a v n =