Suppress Overflow Warnings for Computations Not in the Program

src/analyses/baseInvariant.ml

@@ -798,7 +798,9 @@ struct
                | TInt(ik_e, _)
                | TEnum ({ekind = ik_e; _ }, _) ->
                  (* let c' = ID.cast_to ik_e c in *)
-                 let c' = ID.cast_to ik_e (ID.meet c (ID.cast_to ik (ID.top_of ik_e))) in (* TODO: cast without overflow, is this right for normal invariant? *)
+                 (* Suppressing overflow warnings as this is not a computation that comes from the program *)
+                 let res_range = (ID.cast_to ~suppress_ovwarn:true ik (ID.top_of ik_e)) in
+                 let c' = ID.cast_to ik_e (ID.meet c res_range) in (* TODO: cast without overflow, is this right for normal invariant? *)
                  if M.tracing then M.tracel "inv" "cast: %a from %a to %a: i = %a; cast c = %a to %a = %a" d_exp e d_ikind ik_e d_ikind ik ID.pretty i ID.pretty c d_ikind ik_e ID.pretty c';
                  inv_exp (Int c') e st
                | x -> fallback (fun () -> Pretty.dprintf "CastE: e did evaluate to Int, but the type did not match %a" CilType.Typ.pretty t) st

src/cdomain/value/cdomains/intDomain.ml

@@ -179,7 +179,7 @@ sig
   val maximal    : t -> int_t option
   val minimal    : t -> int_t option
 
-  val cast_to: ?torg:Cil.typ -> Cil.ikind -> t -> t
+  val cast_to: ?suppress_ovwarn:bool -> ?torg:Cil.typ -> Cil.ikind -> t -> t
 end
 
 (** Interface of IntDomain implementations that do not take ikinds for arithmetic operations yet. TODO: Should be ported to S in the future. *)
@@ -208,7 +208,7 @@ sig
   val mul : ?no_ov:bool -> Cil.ikind ->  t -> t -> t
   val div : ?no_ov:bool -> Cil.ikind ->  t -> t -> t
   val neg : ?no_ov:bool -> Cil.ikind ->  t -> t
-  val cast_to : ?torg:Cil.typ -> ?no_ov:bool -> Cil.ikind -> t -> t
+  val cast_to : ?suppress_ovwarn:bool -> ?torg:Cil.typ -> ?no_ov:bool -> Cil.ikind -> t -> t
 
   val join: Cil.ikind -> t -> t -> t
   val meet: Cil.ikind -> t -> t -> t
@@ -247,7 +247,7 @@ sig
 
   val neg : ?no_ov:bool -> Cil.ikind ->  t -> t * overflow_info
 
-  val cast_to : ?torg:Cil.typ -> ?no_ov:bool -> Cil.ikind -> t -> t * overflow_info
+  val cast_to : ?suppress_ovwarn:bool -> ?torg:Cil.typ -> ?no_ov:bool -> Cil.ikind -> t -> t * overflow_info
 
   val of_int : Cil.ikind -> int_t -> t * overflow_info
 
@@ -375,7 +375,7 @@ struct
   let c_logand = lift2 I.c_logand
   let c_logor = lift2 I.c_logor
 
-  let cast_to ?torg ikind x = {v = I.cast_to ~torg:(TInt(x.ikind,[])) ikind x.v; ikind}
+  let cast_to ?(suppress_ovwarn=false) ?torg ikind x = {v = I.cast_to  ~suppress_ovwarn ~torg:(TInt(x.ikind,[])) ikind x.v; ikind}
 
   let is_top_of ik x = ik = x.ikind && I.is_top_of ik x.v
 
@@ -656,7 +656,7 @@ struct
   let maximal = function None -> None | Some (x,y) -> Some y
   let minimal = function None -> None | Some (x,y) -> Some x
 
-  let cast_to ?torg ?no_ov t = norm ~cast:true t (* norm does all overflow handling *)
+  let cast_to ?(suppress_ovwarn=false) ?torg ?no_ov t = norm ~cast:true t (* norm does all overflow handling *)
 
   let widen ik x y =
     match x, y with
@@ -1358,7 +1358,7 @@ struct
     in
     binop x y interval_rem
 
-  let cast_to ?torg ?no_ov ik x = norm_intvs ~cast:true ik x
+  let cast_to ?(suppress_ovwarn=false) ?torg ?no_ov ik x = norm_intvs ~cast:true ik x
 
   (*
       narrows down the extremeties of xs if they are equal to boundary values of the ikind with (possibly) narrower values from ys
@@ -1542,7 +1542,7 @@ module SOverflowUnlifter (D : SOverflow) : S with type int_t = D.int_t and type
 
   let neg ?no_ov ik x = fst @@ D.neg ?no_ov ik x
 
-  let cast_to ?torg ?no_ov ik x = fst @@ D.cast_to ?torg ?no_ov ik x
+  let cast_to ?suppress_ovwarn ?torg ?no_ov ik x = fst @@ D.cast_to ?suppress_ovwarn ?torg ?no_ov ik x
 
   let of_int ik x = fst @@ D.of_int ik x
 
@@ -1612,7 +1612,7 @@ struct
   let c_lognot n1    = of_bool (not (to_bool' n1))
   let c_logand n1 n2 = of_bool ((to_bool' n1) && (to_bool' n2))
   let c_logor  n1 n2 = of_bool ((to_bool' n1) || (to_bool' n2))
-  let cast_to ?torg t x =  failwith @@ "Cast_to not implemented for " ^ (name ()) ^ "."
+  let cast_to ?(suppress_ovwarn=false) ?torg t x =  failwith @@ "Cast_to not implemented for " ^ (name ()) ^ "."
   let arbitrary ik = QCheck.map ~rev:Ints_t.to_int64 Ints_t.of_int64 GobQCheck.Arbitrary.int64 (* TODO: use ikind *)
   let invariant _ _ = Invariant.none (* TODO *)
 end
@@ -1642,7 +1642,7 @@ struct
 
 
   let name () = "flat integers"
-  let cast_to ?torg t = function
+  let cast_to ?(suppress_ovwarn=false) ?torg t = function
     | `Lifted x -> `Lifted (Base.cast_to t x)
     | x -> x
 
@@ -1722,7 +1722,7 @@ struct
   include StdTop (struct type nonrec t = t let top_of = top_of end)
 
   let name () = "lifted integers"
-  let cast_to ?torg t = function
+  let cast_to ?(suppress_ovwarn=false) ?torg t = function
     | `Lifted x -> `Lifted (Base.cast_to t x)
     | x -> x
 
@@ -1907,7 +1907,7 @@ struct
     | `Excluded (s,r) -> if S.mem i s then `Neq else `Top
 
   let top_of ik = `Excluded (S.empty (), size ik)
-  let cast_to ?torg ?no_ov ik = function
+  let cast_to ?(suppress_ovwarn=false) ?torg ?no_ov ik = function
     | `Excluded (s,r) ->
       let r' = size ik in
       if R.leq r r' then (* upcast -> no change *)
@@ -2347,7 +2347,7 @@ struct
   let is_top x = x (* override Std *)
 
   let equal_to i x = if x then `Top else failwith "unsupported: equal_to with bottom"
-  let cast_to ?torg _ x = x (* ok since there's no smaller ikind to cast to *)
+  let cast_to ?(suppress_ovwarn=false) ?torg _ x = x (* ok since there's no smaller ikind to cast to *)
 
   let leq x y = not x || y
   let join = (||)
@@ -2471,7 +2471,7 @@ module Enums : S with type int_t = Z.t = struct
       if BISet.mem i x then `Neq
       else `Top
 
-  let cast_to ?torg ?no_ov ik v = norm ik @@ match v with
+  let cast_to ?(suppress_ovwarn=false) ?torg ?no_ov ik v = norm ik @@ match v with
     | Exc (s,r) ->
       let r' = size ik in
       if R.leq r r' then (* upcast -> no change *)
@@ -2892,7 +2892,7 @@ struct
     | _ -> None
 
   (* cast from original type to ikind, set to top if the value doesn't fit into the new type *)
-  let cast_to ?torg ?(no_ov=false) t x =
+  let cast_to ?(suppress_ovwarn=false) ?torg ?(no_ov=false) t x =
     match x with
     | None -> None
     | Some (c, m) when m =: Z.zero ->
@@ -2916,7 +2916,7 @@ struct
       | _ -> top ()
 
 
-  let cast_to ?torg ?no_ov (t : Cil.ikind) x =
+  let cast_to ?(suppress_ovwarn=false) ?torg ?no_ov (t : Cil.ikind) x =
     let pretty_bool _ x = Pretty.text (string_of_bool x) in
     let res = cast_to ?torg ?no_ov t x in
     if M.tracing then M.trace "cong-cast" "Cast %a to %a (no_ov: %a) = %a" pretty x Cil.d_ikind t (Pretty.docOpt (pretty_bool ())) no_ov pretty res;
@@ -3258,7 +3258,7 @@ module SOverflowLifter (D : S) : SOverflow with type int_t = D.int_t and type t
 
   let neg ?no_ov ik x = lift @@ D.neg ?no_ov ik x
 
-  let cast_to ?torg ?no_ov ik x = lift @@ D.cast_to ?torg ?no_ov ik x
+  let cast_to ?suppress_ovwarn ?torg ?no_ov ik x = lift @@ D.cast_to ?suppress_ovwarn ?torg ?no_ov ik x
 
   let of_int ik x = lift @@ D.of_int ik x
 
@@ -3329,9 +3329,9 @@ module IntDomTupleImpl = struct
     | Some(_, {underflow; overflow}) -> not (underflow || overflow)
     | _ -> false
 
-  let check_ov ~cast ik intv intv_set =
+  let check_ov ?(suppress_ovwarn = false) ~cast ik intv intv_set =
     let no_ov = (no_overflow ik intv) || (no_overflow ik intv_set) in
-    if not no_ov && ( BatOption.is_some intv || BatOption.is_some intv_set) then (
+    if not no_ov && not suppress_ovwarn && ( BatOption.is_some intv || BatOption.is_some intv_set) then (
       let (_,{underflow=underflow_intv; overflow=overflow_intv}) = match intv with None -> (I2.bot (), {underflow= true; overflow = true}) | Some x -> x in
       let (_,{underflow=underflow_intv_set; overflow=overflow_intv_set}) = match intv_set with None -> (I5.bot (), {underflow= true; overflow = true}) | Some x -> x in
       let underflow = underflow_intv && underflow_intv_set in
@@ -3540,11 +3540,11 @@ module IntDomTupleImpl = struct
 
 
   (* map with overflow check *)
-  let mapovc ?(cast=false) ik r (a, b, c, d, e) =
+  let mapovc ?(suppress_ovwarn=false) ?(cast=false) ik r (a, b, c, d, e) =
     let map f ?no_ov = function Some x -> Some (f ?no_ov x) | _ -> None  in
     let intv = map (r.f1_ovc (module I2)) b in
     let intv_set = map (r.f1_ovc (module I5)) e in
-    let no_ov = check_ov ~cast ik intv intv_set in
+    let no_ov = check_ov ~suppress_ovwarn ~cast ik intv intv_set in
     let no_ov = no_ov || should_ignore_overflow ik in
     refine ik
       ( map (fun ?no_ov x -> r.f1_ovc ?no_ov (module I1) x |> fst) a
@@ -3596,8 +3596,8 @@ module IntDomTupleImpl = struct
   let c_lognot ik =
     map ik {f1 = (fun (type a) (module I : SOverflow with type t = a) ?no_ov -> I.c_lognot ik)}
 
-  let cast_to ?torg ?no_ov t =
-    mapovc ~cast:true t {f1_ovc = (fun (type a) (module I : SOverflow with type t = a) ?no_ov -> I.cast_to ?torg ?no_ov t)}
+  let cast_to ?(suppress_ovwarn=false) ?torg ?no_ov t =
+    mapovc ~suppress_ovwarn ~cast:true t {f1_ovc = (fun (type a) (module I : SOverflow with type t = a) ?no_ov -> I.cast_to ?torg ?no_ov t)}
 
   (* fp: projections *)
   let equal_to i x =

src/cdomain/value/cdomains/intDomain.mli

@@ -204,7 +204,7 @@ sig
 
   (** {b Cast} *)
 
-  val cast_to: ?torg:Cil.typ -> Cil.ikind -> t -> t
+  val cast_to: ?suppress_ovwarn:bool -> ?torg:Cil.typ -> Cil.ikind -> t -> t
   (** Cast from original type [torg] to integer type [Cil.ikind]. Currently, [torg] is only present for actual casts. The function is also called to handle overflows/wrap around after operations. In these cases (where the type stays the same) [torg] is None. *)
 
 end
@@ -244,7 +244,7 @@ sig
   val mul : ?no_ov:bool -> Cil.ikind ->  t -> t -> t
   val div : ?no_ov:bool -> Cil.ikind ->  t -> t -> t
   val neg : ?no_ov:bool -> Cil.ikind ->  t -> t
-  val cast_to : ?torg:Cil.typ -> ?no_ov:bool -> Cil.ikind -> t -> t
+  val cast_to : ?suppress_ovwarn:bool -> ?torg:Cil.typ -> ?no_ov:bool -> Cil.ikind -> t -> t
   (** @param no_ov If true, assume no overflow can occur. *)
 
   val join: Cil.ikind -> t ->  t -> t
@@ -290,7 +290,7 @@ sig
 
   val neg : ?no_ov:bool -> Cil.ikind ->  t -> t * overflow_info
 
-  val cast_to : ?torg:Cil.typ -> ?no_ov:bool -> Cil.ikind -> t -> t * overflow_info
+  val cast_to : ?suppress_ovwarn:bool -> ?torg:Cil.typ -> ?no_ov:bool -> Cil.ikind -> t -> t * overflow_info
 
   val of_int : Cil.ikind -> int_t -> t * overflow_info
 

tests/regression/27-inv_invariants/20-warns-unsigned.c

@@ -0,0 +1,22 @@
+// PARAM: --enable ana.int.interval
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+
+int main() {
+  unsigned int length = 5;
+  int i = 0;
+  int top;
+
+  if(top) {
+    i = 10;
+  }
+
+  // Previously, we would warn as invariant internally casts an artificially created top between types.
+  if(i < length + 3) //NOWARN
+  {
+    __goblint_check(i <= 8);
+    i = 8;
+  }
+}