[pulse] add a bunch of equal and compare functions

Summary:
This is all dead code but I had to do this to try something else and I
don't want to have to do that again :)

Reviewed By: skcho

Differential Revision: D26022111

fbshipit-source-id: 622ca10b9

infer/src/absint/HilExp.ml

@@ -15,13 +15,15 @@ let yojson_of_typ_ = [%yojson_of: _]
 
 let compare_typ_ _ _ = 0
 
+let equal_typ_ = [%compare.equal: typ_]
+
 module Access = struct
   type ('fieldname, 'array_index) t_ =
     | FieldAccess of 'fieldname
     | ArrayAccess of typ_ * 'array_index
     | TakeAddress
     | Dereference
-  [@@deriving compare, yojson_of]
+  [@@deriving compare, equal, yojson_of]
 
   type 'array_index t = (Fieldname.t, 'array_index) t_ [@@deriving compare, yojson_of]
 

infer/src/absint/HilExp.mli

@@ -14,7 +14,7 @@ module Access : sig
     | ArrayAccess of Typ.t * 'array_index
     | TakeAddress
     | Dereference
-  [@@deriving compare, yojson_of]
+  [@@deriving compare, equal, yojson_of]
 
   type 'array_index t = (Fieldname.t, 'array_index) t_ [@@deriving compare, yojson_of]
 

infer/src/bufferoverrun/itv.ml

@@ -43,7 +43,7 @@ end
 
 module ItvPure = struct
   (** (l, u) represents the closed interval [l; u] (of course infinite bounds are open) *)
-  type t = Bound.t * Bound.t [@@deriving compare]
+  type t = Bound.t * Bound.t [@@deriving compare, equal]
 
   let lb : t -> Bound.t = fst
 

infer/src/bufferoverrun/itv.mli

@@ -19,7 +19,7 @@ module ItvRange : sig
 end
 
 module ItvPure : sig
-  type t [@@deriving compare]
+  type t [@@deriving compare, equal]
 
   val pp : F.formatter -> t -> unit
 

infer/src/istd/PrettyPrintable.ml

@@ -221,7 +221,7 @@ module type PrintableRankedType = sig
 end
 
 module type PPUniqRankSet = sig
-  type t
+  type t [@@deriving compare, equal]
 
   type rank
 
@@ -231,8 +231,6 @@ module type PPUniqRankSet = sig
 
   val empty : t
 
-  val equal : t -> t -> bool
-
   val find_rank : t -> rank -> elt option
 
   val fold : t -> init:'accum -> f:('accum -> elt -> 'accum) -> 'accum
@@ -278,6 +276,8 @@ module MakePPUniqRankSet
 
   let empty = Map.empty
 
+  let compare = Map.compare Val.compare
+
   let equal = Map.equal Val.equal
 
   let find_rank m rank = Map.find_opt rank m

infer/src/istd/PrettyPrintable.mli

@@ -172,7 +172,7 @@ end
 
 (** set where at most one element of a given rank can be present *)
 module type PPUniqRankSet = sig
-  type t
+  type t [@@deriving compare, equal]
 
   type rank
 
@@ -182,8 +182,6 @@ module type PPUniqRankSet = sig
 
   val empty : t
 
-  val equal : t -> t -> bool
-
   val find_rank : t -> rank -> elt option
 
   val fold : t -> init:'accum -> f:('accum -> elt -> 'accum) -> 'accum

infer/src/istd/RecencyMap.ml

@@ -13,7 +13,7 @@ module type Config = sig
 end
 
 module type S = sig
-  type t
+  type t [@@deriving compare, equal]
 
   type key
 
@@ -48,10 +48,14 @@ module Make
     (Key : PrettyPrintable.PrintableEquatableOrderedType)
     (Value : PrettyPrintable.PrintableOrderedType)
     (Config : Config) : S with type key = Key.t and type value = Value.t = struct
-  type key = Key.t
+  type key = Key.t [@@deriving compare]
 
   type value = Value.t [@@deriving compare]
 
+  (* suppress warnings about using {!List.Assoc.compare} since our own compare function also ignores
+     that different representations of a [t] can have the same meaning *)
+  [@@@warning "-3"]
+
   (** [new_] and [old] together represent the map. Keys may be present in both [old] and [new_], in
       which case bindings in [new_] take precendence.
 
@@ -68,6 +72,11 @@ module Make
     ; old: (key, value) List.Assoc.t
           (** invariant: [List.length old ≤ Config.limit]. Actually, the length of [old] is always
               either [0] or [N], except possibly after a call to [merge]. *) }
+  [@@deriving compare]
+
+  [@@@warning "+3"]
+
+  let equal = [%compare.equal: t]
 
   let empty = {count_new= 0; old= []; new_= []}
 
@@ -126,8 +135,6 @@ module Make
     else {count_new= next_count_new; new_= (key, value) :: new_without_key; old= map.old}
 
 
-  let equal map1 map2 = phys_equal map1 map2
-
   let fold map ~init ~f =
     let acc = List.fold map.new_ ~init ~f in
     (* this is quadratic time but the lists are at most [Config.limit] long, assumed small *)

infer/src/istd/RecencyMap.mli

@@ -16,14 +16,14 @@ end
 (** A functional map interface where only the [N] most recently-accessed elements are guaranteed to
     be persisted, similarly to an LRU cache. The map stores at most [2*N] elements. *)
 module type S = sig
-  type t
+  (** Note that the derived [compare] and [equal] functions are sensitive to the underlying
+      implementation and in particular won't equate some objects that denote the same map. *)
+  type t [@@deriving compare, equal]
 
   type key
 
   type value
 
-  val equal : t -> t -> bool
-
   val pp : F.formatter -> t -> unit
 
   val empty : t

infer/src/istd/UnionFind.ml

@@ -26,7 +26,7 @@ struct
     (** to get a little bit of type safety *)
     type repr = private X.t
 
-    type t
+    type t [@@deriving compare, equal]
 
     val empty : t
 
@@ -43,7 +43,7 @@ struct
   end = struct
     type repr = X.t
 
-    type t = X.t XMap.t
+    type t = X.t XMap.t [@@deriving compare, equal]
 
     let empty = XMap.empty
 
@@ -82,7 +82,7 @@ struct
       UF.Map.remove x1 classes |> UF.Map.add x2 new_class
   end
 
-  type t = {reprs: UF.t; classes: XSet.t UF.Map.t}
+  type t = {reprs: UF.t; classes: XSet.t UF.Map.t} [@@deriving compare, equal]
 
   let empty = {reprs= UF.empty; classes= UF.Map.empty}
 

infer/src/istd/UnionFind.mli

@@ -21,7 +21,7 @@ module Make
     (X : Element)
     (XSet : Caml.Set.S with type elt = X.t)
     (XMap : Caml.Map.S with type key = X.t) : sig
-  type t
+  type t [@@deriving compare, equal]
 
   val pp :
     pp_empty:(F.formatter -> unit) -> (F.formatter -> X.t -> unit) -> F.formatter -> t -> unit

infer/src/pulse/PulseAbductiveDomain.ml

@@ -19,7 +19,7 @@ module BaseAddressAttributes = PulseBaseAddressAttributes
 module type BaseDomainSig = sig
   (* private because the lattice is not the same for preconditions and postconditions so we don't
      want to confuse them *)
-  type t = private BaseDomain.t [@@deriving yojson_of]
+  type t = private BaseDomain.t [@@deriving compare, equal, yojson_of]
 
   val empty : t
 
@@ -86,7 +86,7 @@ end
 (** represents the inferred pre-condition at each program point, biabduction style *)
 module PreDomain : BaseDomainSig = PostDomain
 
-type isl_status = ISLOk | ISLError [@@deriving equal, yojson_of]
+type isl_status = ISLOk | ISLError [@@deriving compare, equal, yojson_of]
 
 let pp_isl_status f s =
   if Config.pulse_isl then
@@ -106,7 +106,7 @@ type t =
   ; topl: (PulseTopl.state[@yojson.opaque])
   ; skipped_calls: SkippedCalls.t
   ; isl_status: isl_status }
-[@@deriving yojson_of]
+[@@deriving compare, equal, yojson_of]
 
 let pp f {post; pre; topl; path_condition; skipped_calls; isl_status} =
   F.fprintf f "@[<v>%a@;%a@;%a@;PRE=[%a]@;skipped_calls=%a@;TOPL=%a@]" PathCondition.pp
@@ -628,7 +628,7 @@ let invalidate_locals pdesc astate : t =
   else {astate with post= PostDomain.update astate.post ~attrs:attrs'}
 
 
-type summary = t [@@deriving yojson_of]
+type summary = t [@@deriving compare, equal, yojson_of]
 
 let is_allocated {post; pre} v =
   let is_pvar = function Var.ProgramVar _ -> true | Var.LogicalVar _ -> false in

infer/src/pulse/PulseAbductiveDomain.mli

@@ -23,7 +23,7 @@ module BaseStack = PulseBaseStack
 module type BaseDomainSig = sig
   (* private because the lattice is not the same for preconditions and postconditions so we don't
      want to confuse them *)
-  type t = private BaseDomain.t [@@deriving yojson_of]
+  type t = private BaseDomain.t [@@deriving compare, equal, yojson_of]
 
   val yojson_of_t : t -> Yojson.Safe.t
 
@@ -73,6 +73,7 @@ type t = private
         (** state at of the Topl monitor at the current program point, when Topl is enabled *)
   ; skipped_calls: SkippedCalls.t  (** metadata: procedure calls for which no summary was found *)
   ; isl_status: isl_status }
+[@@deriving equal]
 
 val leq : lhs:t -> rhs:t -> bool
 
@@ -189,7 +190,7 @@ val add_skipped_calls : SkippedCalls.t -> t -> t
 val set_path_condition : PathCondition.t -> t -> t
 
 (** private type to make sure {!summary_of_post} is always called when creating summaries *)
-type summary = private t [@@deriving yojson_of]
+type summary = private t [@@deriving compare, equal, yojson_of]
 
 val summary_of_post : Procdesc.t -> t -> summary SatUnsat.t
 (** trim the state down to just the procedure's interface (formals and globals), and simplify and

infer/src/pulse/PulseBaseAddressAttributes.ml

@@ -19,6 +19,10 @@ module Graph = PrettyPrintable.MakePPMonoMap (AbstractValue) (AttributesNoRank)
 
 type t = Graph.t
 
+let compare = Graph.compare AttributesNoRank.compare
+
+let equal = Graph.equal AttributesNoRank.equal
+
 let yojson_of_t = [%yojson_of: _]
 
 let add_one addr attribute attrs =

infer/src/pulse/PulseBaseAddressAttributes.mli

@@ -8,7 +8,7 @@ open! IStd
 module F = Format
 open PulseBasicInterface
 
-type t [@@deriving yojson_of]
+type t [@@deriving compare, equal, yojson_of]
 
 val empty : t
 

infer/src/pulse/PulseBaseDomain.ml

@@ -14,7 +14,8 @@ module AddressAttributes = PulseBaseAddressAttributes
 
 (* {2 Abstract domain description } *)
 
-type t = {heap: Memory.t; stack: Stack.t; attrs: AddressAttributes.t} [@@deriving yojson_of]
+type t = {heap: Memory.t; stack: Stack.t; attrs: AddressAttributes.t}
+[@@deriving compare, equal, yojson_of]
 
 let empty =
   { heap=

infer/src/pulse/PulseBaseDomain.mli

@@ -10,7 +10,7 @@ open PulseBasicInterface
 module F = Format
 
 type t = {heap: PulseBaseMemory.t; stack: PulseBaseStack.t; attrs: PulseBaseAddressAttributes.t}
-[@@deriving yojson_of]
+[@@deriving compare, equal, yojson_of]
 
 type cell = PulseBaseMemory.Edges.t * Attributes.t
 

infer/src/pulse/PulseBaseMemory.ml

@@ -104,3 +104,7 @@ let canonicalize ~get_var_repr memory =
 
 
 include Graph
+
+let compare = Graph.compare Edges.compare
+
+let equal = Graph.equal Edges.equal

infer/src/pulse/PulseBaseMemory.mli

@@ -24,6 +24,10 @@ module Edges : RecencyMap.S with type key = Access.t and type value = AddrTrace.
 
 include PrettyPrintable.PPMonoMap with type key = AbstractValue.t and type value = Edges.t
 
+val compare : t -> t -> int
+
+val equal : t -> t -> bool
+
 val register_address : AbstractValue.t -> t -> t
 
 val add_edge : AbstractValue.t -> Access.t -> AddrTrace.t -> t -> t

infer/src/pulse/PulseBaseStack.ml

@@ -19,7 +19,7 @@ module VarAddress = struct
 end
 
 module AddrHistPair = struct
-  type t = AbstractValue.t * ValueHistory.t [@@deriving compare, yojson_of]
+  type t = AbstractValue.t * ValueHistory.t [@@deriving compare, equal, yojson_of]
 
   let pp f addr_trace =
     if Config.debug_level_analysis >= 3 then
@@ -50,6 +50,8 @@ include M
 
 let compare = M.compare AddrHistPair.compare
 
+let equal = M.equal AddrHistPair.equal
+
 let pp fmt m =
   let pp_item fmt (var_address, v) =
     F.fprintf fmt "%a=%a" VarAddress.pp var_address AddrHistPair.pp v

infer/src/pulse/PulseBaseStack.mli

@@ -15,6 +15,8 @@ include
      different type *)
 val compare : t -> t -> int [@@warning "-32"]
 
+val equal : t -> t -> bool
+
 val pp : F.formatter -> t -> unit
 
 val yojson_of_t : t -> Yojson.Safe.t

infer/src/pulse/PulseCItv.ml

@@ -10,7 +10,7 @@ module F = Format
 module L = Logging
 
 module Bound = struct
-  type t = Int of IntLit.t | MinusInfinity | PlusInfinity [@@deriving compare]
+  type t = Int of IntLit.t | MinusInfinity | PlusInfinity [@@deriving compare, equal]
 
   let pp fmt = function
     | Int i ->
@@ -112,7 +112,7 @@ module Unsafe : sig
   type t = private
     | Between of Bound.t * Bound.t  (** we write \[b1,b2\] for these *)
     | Outside of IntLit.t * IntLit.t  (** we write i1\]\[i2 for these *)
-  [@@deriving compare]
+  [@@deriving compare, equal]
 
   val between : Bound.t -> Bound.t -> t
 
@@ -124,7 +124,8 @@ module Unsafe : sig
 
   val ge_to : IntLit.t -> t
 end = struct
-  type t = Between of Bound.t * Bound.t | Outside of IntLit.t * IntLit.t [@@deriving compare]
+  type t = Between of Bound.t * Bound.t | Outside of IntLit.t * IntLit.t
+  [@@deriving compare, equal]
 
   let between b1 b2 =
     assert (Bound.is_interval b1 b2) ;

infer/src/pulse/PulseCItv.mli

@@ -9,7 +9,7 @@ module F = Format
 
 (** Concrete interval domain (CItv) *)
 
-type t [@@deriving compare]
+type t [@@deriving compare, equal]
 
 val equal_to : IntLit.t -> t
 

infer/src/pulse/PulseDiagnostic.ml

@@ -17,10 +17,10 @@ type access_to_invalid_address =
   ; invalidation: Invalidation.t
   ; invalidation_trace: Trace.t
   ; access_trace: Trace.t }
-[@@deriving equal]
+[@@deriving compare, equal]
 
 type read_uninitialized_value = {calling_context: (CallEvent.t * Location.t) list; trace: Trace.t}
-[@@deriving equal]
+[@@deriving compare, equal]
 
 let yojson_of_access_to_invalid_address = [%yojson_of: _]
 

infer/src/pulse/PulseDiagnostic.mli

@@ -22,7 +22,7 @@ type access_to_invalid_address =
   ; access_trace: Trace.t
         (** assuming we are in the calling context, the trace leads to an access to the value
             invalidated in [invalidation_trace] without further assumptions *) }
-[@@deriving equal, yojson_of]
+[@@deriving compare, equal, yojson_of]
 
 type read_uninitialized_value =
   { calling_context: (CallEvent.t * Location.t) list
@@ -31,7 +31,7 @@ type read_uninitialized_value =
   ; trace: Trace.t
         (** assuming we are in the calling context, the trace leads to read of the uninitialized
             value *) }
-[@@deriving equal, yojson_of]
+[@@deriving compare, equal, yojson_of]
 
 (** an error to report to the user *)
 type t =

infer/src/pulse/PulseExecutionDomain.ml

@@ -22,7 +22,7 @@ type 'abductive_domain_t base_t =
   | AbortProgram of AbductiveDomain.summary
   | LatentAbortProgram of {astate: AbductiveDomain.summary; latent_issue: LatentIssue.t}
   | ISLLatentMemoryError of 'abductive_domain_t
-[@@deriving yojson_of]
+[@@deriving equal, compare, yojson_of]
 
 type t = AbductiveDomain.t base_t
 
@@ -76,7 +76,7 @@ let get_astate : t -> AbductiveDomain.t = function
 
 let is_unsat_cheap exec_state = PathCondition.is_unsat_cheap (get_astate exec_state).path_condition
 
-type summary = AbductiveDomain.summary base_t [@@deriving yojson_of]
+type summary = AbductiveDomain.summary base_t [@@deriving compare, equal, yojson_of]
 
 let summary_of_posts_common ~continue_program pdesc posts =
   List.filter_mapi posts ~f:(fun i exec_state ->

infer/src/pulse/PulseExecutionDomain.mli

@@ -32,7 +32,7 @@ val mk_initial : Procdesc.t -> t
 val is_unsat_cheap : t -> bool
 (** see {!PulsePathCondition.is_unsat_cheap} *)
 
-type summary = AbductiveDomain.summary base_t [@@deriving yojson_of]
+type summary = AbductiveDomain.summary base_t [@@deriving compare, equal, yojson_of]
 
 val summary_of_posts : Procdesc.t -> t list -> summary list
 

infer/src/pulse/PulseFormula.ml

@@ -48,7 +48,7 @@ end
 (** Linear Arithmetic *)
 module LinArith : sig
   (** linear combination of variables, eg [2·x + 3/4·y + 12] *)
-  type t [@@deriving compare, yojson_of]
+  type t [@@deriving compare, yojson_of, equal]
 
   type subst_target = QSubst of Q.t | VarSubst of Var.t | LinSubst of t
 
@@ -239,7 +239,7 @@ module Term = struct
     | BitShiftLeft of t * t
     | BitShiftRight of t * t
     | BitXor of t * t
-  [@@deriving compare, yojson_of]
+  [@@deriving compare, equal, yojson_of]
 
   let equal_syntax = [%compare.equal: t]
 
@@ -703,7 +703,7 @@ module Atom = struct
     | LessThan of Term.t * Term.t
     | Equal of Term.t * Term.t
     | NotEqual of Term.t * Term.t
-  [@@deriving compare, yojson_of]
+  [@@deriving compare, equal, yojson_of]
 
   let pp_with_pp_var pp_var fmt atom =
     (* add parens around terms that look like atoms to disambiguate *)
@@ -973,7 +973,7 @@ type new_eqs = new_eq list
 
 module Formula = struct
   (* redefined for yojson output *)
-  type var_eqs = VarUF.t
+  type var_eqs = VarUF.t [@@deriving compare, equal]
 
   let yojson_of_var_eqs var_eqs =
     `List
@@ -983,7 +983,7 @@ module Formula = struct
            :: jsons ))
 
 
-  type linear_eqs = LinArith.t Var.Map.t
+  type linear_eqs = LinArith.t Var.Map.t [@@deriving compare, equal]
 
   let yojson_of_linear_eqs linear_eqs = Var.Map.yojson_of_t LinArith.yojson_of_t linear_eqs
 
@@ -992,7 +992,7 @@ module Formula = struct
     ; linear_eqs: linear_eqs
           (** equalities of the form [x = l] where [l] is from linear arithmetic *)
     ; atoms: Atom.Set.t  (** not always normalized w.r.t. [var_eqs] and [linear_eqs] *) }
-  [@@deriving yojson_of]
+  [@@deriving compare, equal, yojson_of]
 
   let ttrue = {var_eqs= VarUF.empty; linear_eqs= Var.Map.empty; atoms= Atom.Set.empty}
 
@@ -1275,6 +1275,13 @@ type t =
   ; both: Formula.t  (** [both = known ∧ pruned], allows us to detect contradictions *) }
 [@@deriving yojson_of]
 
+let compare phi1 phi2 =
+  if phys_equal phi1 phi2 then 0
+  else [%compare: Atom.Set.t * Formula.t] (phi1.pruned, phi1.known) (phi2.pruned, phi2.known)
+
+
+let equal = [%compare.equal: t]
+
 let ttrue = {known= Formula.ttrue; pruned= Atom.Set.empty; both= Formula.ttrue}
 
 let pp_with_pp_var pp_var fmt {known; pruned; both} =

infer/src/pulse/PulseFormula.mli

@@ -17,7 +17,7 @@ module Var = PulseAbstractValue
 
     Build formulas from SIL and tries to decide if they are (mostly un-)satisfiable. *)
 
-type t [@@deriving yojson_of]
+type t [@@deriving compare, equal, yojson_of]
 
 val pp : F.formatter -> t -> unit
 

infer/src/pulse/PulseLatentIssue.ml

@@ -13,7 +13,7 @@ module Arithmetic = PulseArithmetic
 type t =
   | AccessToInvalidAddress of Diagnostic.access_to_invalid_address
   | ReadUninitializedValue of Diagnostic.read_uninitialized_value
-[@@deriving equal, yojson_of]
+[@@deriving compare, equal, yojson_of]
 
 let to_diagnostic = function
   | AccessToInvalidAddress access_to_invalid_address ->

infer/src/pulse/PulseLatentIssue.mli

@@ -16,7 +16,7 @@ module AbductiveDomain = PulseAbductiveDomain
 type t =
   | AccessToInvalidAddress of Diagnostic.access_to_invalid_address
   | ReadUninitializedValue of Diagnostic.read_uninitialized_value
-[@@deriving equal, yojson_of]
+[@@deriving compare, equal, yojson_of]
 
 val to_diagnostic : t -> Diagnostic.t
 

infer/src/pulse/PulsePathCondition.ml

@@ -36,6 +36,13 @@ type t =
   ; citvs: CItvs.t
   ; formula: Formula.t }
 
+let compare phi1 phi2 =
+  if phys_equal phi1 phi2 || (phi1.is_unsat && phi2.is_unsat) then 0
+  else [%compare: bool * Formula.t] (phi1.is_unsat, phi1.formula) (phi2.is_unsat, phi2.formula)
+
+
+let equal = [%compare.equal: t]
+
 let yojson_of_t {formula} = [%yojson_of: Formula.t] formula
 
 let pp fmt {is_unsat; bo_itvs; citvs; formula} =

infer/src/pulse/PulsePathCondition.mli

@@ -11,7 +11,7 @@ module AbstractValue = PulseAbstractValue
 module SatUnsat = PulseSatUnsat
 module ValueHistory = PulseValueHistory
 
-type t [@@deriving yojson_of]
+type t [@@deriving compare, equal, yojson_of]
 
 val true_ : t
 

infer/src/pulse/PulseSkippedCalls.ml

@@ -9,7 +9,7 @@ open! IStd
 module F = Format
 
 module SkippedTrace = struct
-  type t = PulseTrace.t [@@deriving compare]
+  type t = PulseTrace.t [@@deriving compare, equal]
 
   let pp fmt =
     PulseTrace.pp fmt ~pp_immediate:(fun fmt ->
@@ -26,6 +26,10 @@ end
 module M = AbstractDomain.Map (Procname) (SkippedTrace)
 include M
 
+let compare = M.compare SkippedTrace.compare
+
+let equal = M.equal SkippedTrace.equal
+
 let yojson_of_t = [%yojson_of: _]
 
 (* ignore traces, just compare if the set of skipped procedures is the same *)

infer/src/pulse/PulseSkippedCalls.mli

@@ -9,4 +9,8 @@ open! IStd
 
 include AbstractDomain.MapS with type key = Procname.t and type value = PulseTrace.t
 
+val compare : t -> t -> int
+
+val equal : t -> t -> bool
+
 val yojson_of_t : t -> Yojson.Safe.t

infer/src/pulse/PulseTopl.ml

@@ -202,9 +202,11 @@ and simple_state =
   ; last_step: step option [@compare.ignore]  (** for trace error reporting *) }
 [@@deriving compare]
 
+let equal_simple_state = [%compare.equal: simple_state]
+
 (* TODO: include a hash of the automaton in a summary to avoid caching problems. *)
 (* TODO: limit the number of simple_states to some configurable number (default ~5) *)
-type state = simple_state list
+type state = simple_state list [@@deriving compare, equal]
 
 let pp_mapping f (x, value) = Format.fprintf f "@[%s↦%a@]@," x AbstractValue.pp value
 

infer/src/pulse/PulseTopl.mli

@@ -13,7 +13,7 @@ type event =
   | ArrayWrite of {aw_array: value; aw_index: value}
   | Call of {return: value option; arguments: value list; procname: Procname.t}
 
-type state
+type state [@@deriving compare, equal]
 
 val start : unit -> state
 (** Return the initial state of [Topl.automaton ()]. *)