[pulse][formula] print readable variable names in unit tests

Summary:
Perhaps a bit overkill to introduce all this extra complexity but it
makes the unit tests much more readable.  In fact, this uncovered a bug
in the dead variable elimination!

Reviewed By: dulmarod

Differential Revision: D22925548

fbshipit-source-id: d1f411683

infer/src/pulse/PulseFormula.ml

@@ -66,56 +66,60 @@ module Term = struct
         true
 
 
-  let rec pp_paren ~needs_paren fmt t =
-    if needs_paren t then F.fprintf fmt "(%a)" pp_no_paren t else pp_no_paren fmt t
+  let rec pp_paren pp_var ~needs_paren fmt t =
+    if needs_paren t then F.fprintf fmt "(%a)" (pp_no_paren pp_var) t else pp_no_paren pp_var fmt t
 
 
-  and pp_no_paren fmt = function
+  and pp_no_paren pp_var fmt = function
     | Var v ->
-        AbstractValue.pp fmt v
+        pp_var fmt v
     | Const c ->
         Const.pp Pp.text fmt c
     | Minus t ->
-        F.fprintf fmt "-%a" (pp_paren ~needs_paren) t
+        F.fprintf fmt "-%a" (pp_paren pp_var ~needs_paren) t
     | BitNot t ->
-        F.fprintf fmt "BitNot%a" (pp_paren ~needs_paren) t
+        F.fprintf fmt "BitNot%a" (pp_paren pp_var ~needs_paren) t
     | Not t ->
-        F.fprintf fmt "¬%a" (pp_paren ~needs_paren) t
+        F.fprintf fmt "¬%a" (pp_paren pp_var ~needs_paren) t
     | Add (t1, Minus t2) ->
-        F.fprintf fmt "%a-%a" (pp_paren ~needs_paren) t1 (pp_paren ~needs_paren) t2
+        F.fprintf fmt "%a-%a" (pp_paren pp_var ~needs_paren) t1 (pp_paren pp_var ~needs_paren) t2
     | Add (t1, t2) ->
-        F.fprintf fmt "%a+%a" (pp_paren ~needs_paren) t1 (pp_paren ~needs_paren) t2
+        F.fprintf fmt "%a+%a" (pp_paren pp_var ~needs_paren) t1 (pp_paren pp_var ~needs_paren) t2
     | Mult (t1, t2) ->
-        F.fprintf fmt "%a×%a" (pp_paren ~needs_paren) t1 (pp_paren ~needs_paren) t2
+        F.fprintf fmt "%a×%a" (pp_paren pp_var ~needs_paren) t1 (pp_paren pp_var ~needs_paren) t2
     | Div (t1, t2) ->
-        F.fprintf fmt "%a÷%a" (pp_paren ~needs_paren) t1 (pp_paren ~needs_paren) t2
+        F.fprintf fmt "%a÷%a" (pp_paren pp_var ~needs_paren) t1 (pp_paren pp_var ~needs_paren) t2
     | Mod (t1, t2) ->
-        F.fprintf fmt "%a mod %a" (pp_paren ~needs_paren) t1 (pp_paren ~needs_paren) t2
+        F.fprintf fmt "%a mod %a" (pp_paren pp_var ~needs_paren) t1 (pp_paren pp_var ~needs_paren)
+          t2
     | BitAnd (t1, t2) ->
-        F.fprintf fmt "%a&%a" (pp_paren ~needs_paren) t1 (pp_paren ~needs_paren) t2
+        F.fprintf fmt "%a&%a" (pp_paren pp_var ~needs_paren) t1 (pp_paren pp_var ~needs_paren) t2
     | BitOr (t1, t2) ->
-        F.fprintf fmt "%a|%a" (pp_paren ~needs_paren) t1 (pp_paren ~needs_paren) t2
+        F.fprintf fmt "%a|%a" (pp_paren pp_var ~needs_paren) t1 (pp_paren pp_var ~needs_paren) t2
     | BitShiftLeft (t1, t2) ->
-        F.fprintf fmt "%a<<%a" (pp_paren ~needs_paren) t1 (pp_paren ~needs_paren) t2
+        F.fprintf fmt "%a<<%a" (pp_paren pp_var ~needs_paren) t1 (pp_paren pp_var ~needs_paren) t2
     | BitShiftRight (t1, t2) ->
-        F.fprintf fmt "%a>>%a" (pp_paren ~needs_paren) t1 (pp_paren ~needs_paren) t2
+        F.fprintf fmt "%a>>%a" (pp_paren pp_var ~needs_paren) t1 (pp_paren pp_var ~needs_paren) t2
     | BitXor (t1, t2) ->
-        F.fprintf fmt "%a xor %a" (pp_paren ~needs_paren) t1 (pp_paren ~needs_paren) t2
+        F.fprintf fmt "%a xor %a" (pp_paren pp_var ~needs_paren) t1 (pp_paren pp_var ~needs_paren)
+          t2
     | And (t1, t2) ->
-        F.fprintf fmt "%a∧%a" (pp_paren ~needs_paren) t1 (pp_paren ~needs_paren) t2
+        F.fprintf fmt "%a∧%a" (pp_paren pp_var ~needs_paren) t1 (pp_paren pp_var ~needs_paren) t2
     | Or (t1, t2) ->
-        F.fprintf fmt "%a∨%a" (pp_paren ~needs_paren) t1 (pp_paren ~needs_paren) t2
+        F.fprintf fmt "%a∨%a" (pp_paren pp_var ~needs_paren) t1 (pp_paren pp_var ~needs_paren) t2
     | LessThan (t1, t2) ->
-        F.fprintf fmt "%a<%a" (pp_paren ~needs_paren) t1 (pp_paren ~needs_paren) t2
+        F.fprintf fmt "%a<%a" (pp_paren pp_var ~needs_paren) t1 (pp_paren pp_var ~needs_paren) t2
     | LessEqual (t1, t2) ->
-        F.fprintf fmt "%a≤%a" (pp_paren ~needs_paren) t1 (pp_paren ~needs_paren) t2
+        F.fprintf fmt "%a≤%a" (pp_paren pp_var ~needs_paren) t1 (pp_paren pp_var ~needs_paren) t2
     | Equal (t1, t2) ->
-        F.fprintf fmt "%a=%a" (pp_paren ~needs_paren) t1 (pp_paren ~needs_paren) t2
+        F.fprintf fmt "%a=%a" (pp_paren pp_var ~needs_paren) t1 (pp_paren pp_var ~needs_paren) t2
     | NotEqual (t1, t2) ->
-        F.fprintf fmt "%a≠%a" (pp_paren ~needs_paren) t1 (pp_paren ~needs_paren) t2
+        F.fprintf fmt "%a≠%a" (pp_paren pp_var ~needs_paren) t1 (pp_paren pp_var ~needs_paren) t2
 
 
-  let pp fmt t = pp_no_paren fmt t
+  let pp_with_pp_var pp_var fmt t = pp_no_paren pp_var fmt t
+
+  let pp fmt t = pp_with_pp_var AbstractValue.pp fmt t
 
   let of_absval v = Var v
 
@@ -292,21 +296,24 @@ module Atom = struct
 
   type atom = t
 
-  let pp fmt atom =
+  let pp_with_pp_var pp_var fmt atom =
     (* add parens around terms that look like atoms to disambiguate *)
     let needs_paren (t : Term.t) =
       match t with LessThan _ | LessEqual _ | Equal _ | NotEqual _ -> true | _ -> false
     in
+    let pp_term = Term.pp_paren pp_var ~needs_paren in
     match atom with
     | LessEqual (t1, t2) ->
-        F.fprintf fmt "%a ≤ %a" (Term.pp_paren ~needs_paren) t1 (Term.pp_paren ~needs_paren) t2
+        F.fprintf fmt "%a ≤ %a" pp_term t1 pp_term t2
     | LessThan (t1, t2) ->
-        F.fprintf fmt "%a < %a" (Term.pp_paren ~needs_paren) t1 (Term.pp_paren ~needs_paren) t2
+        F.fprintf fmt "%a < %a" pp_term t1 pp_term t2
     | Equal (t1, t2) ->
-        F.fprintf fmt "%a = %a" (Term.pp_paren ~needs_paren) t1 (Term.pp_paren ~needs_paren) t2
+        F.fprintf fmt "%a = %a" pp_term t1 pp_term t2
     | NotEqual (t1, t2) ->
-        F.fprintf fmt "%a ≠ %a" (Term.pp_paren ~needs_paren) t1 (Term.pp_paren ~needs_paren) t2
+        F.fprintf fmt "%a ≠ %a" pp_term t1 pp_term t2
+
 
+  let pp = pp_with_pp_var AbstractValue.pp
 
   let nnot = function
     | LessEqual (t1, t2) ->
@@ -549,13 +556,13 @@ let is_literal_false = function False -> true | _ -> false
 
 let ttrue = True
 
-let rec pp fmt = function
+let rec pp_with_pp_var pp_var fmt = function
   | True ->
       F.fprintf fmt "true"
   | False ->
       F.fprintf fmt "false"
   | Atom atom ->
-      Atom.pp fmt atom
+      Atom.pp_with_pp_var pp_var fmt atom
   | NormalForm {congruences; facts} ->
       let pp_collection ~fold ~sep ~pp_item fmt coll =
         let pp_coll_aux is_first item =
@@ -564,7 +571,7 @@ let rec pp fmt = function
         in
         F.fprintf fmt "@[<hv>%t@]" (fun _fmt -> fold coll ~init:true ~f:pp_coll_aux |> ignore)
       in
-      let term_pp_paren = Term.pp_paren ~needs_paren:Term.needs_paren in
+      let term_pp_paren = Term.pp_paren pp_var ~needs_paren:Term.needs_paren in
       let pp_ts_or_repr repr fmt ts =
         if UnionFind.Set.is_empty ts then term_pp_paren fmt repr
         else
@@ -578,20 +585,22 @@ let rec pp fmt = function
           ~pp_item:(fun fmt ((repr : UnionFind.repr), ts) ->
             is_empty := false ;
             F.fprintf fmt "%a=%a" term_pp_paren (repr :> Term.t) (pp_ts_or_repr (repr :> Term.t)) ts ) ;
-        if !is_empty then pp fmt True
+        if !is_empty then pp_with_pp_var pp_var fmt True
       in
       let pp_atoms fmt atoms =
-        if Atom.Set.is_empty atoms then pp fmt True
+        if Atom.Set.is_empty atoms then pp_with_pp_var pp_var fmt True
         else
           pp_collection ~sep:"∧"
             ~fold:(IContainer.fold_of_pervasives_set_fold Atom.Set.fold)
-            ~pp_item:(fun fmt atom -> F.fprintf fmt "{%a}" Atom.pp atom)
+            ~pp_item:(fun fmt atom -> F.fprintf fmt "{%a}" (Atom.pp_with_pp_var pp_var) atom)
             fmt atoms
       in
       F.fprintf fmt "[@[<hv>%a@ &&@ %a@]]" pp_congruences congruences pp_atoms facts
   | And (phi1, phi2) ->
-      F.fprintf fmt "{%a}∧{%a}" pp phi1 pp phi2
+      F.fprintf fmt "{%a}∧{%a}" (pp_with_pp_var pp_var) phi1 (pp_with_pp_var pp_var) phi2
+
 
+let pp = pp_with_pp_var AbstractValue.pp
 
 module NormalForm : sig
   val of_formula : t -> t

infer/src/pulse/PulseFormula.mli

@@ -34,6 +34,10 @@ type t
 
 val pp : F.formatter -> t -> unit
 
+val pp_with_pp_var : (F.formatter -> AbstractValue.t -> unit) -> F.formatter -> t -> unit
+  [@@warning "-32"]
+(** only used for unit tests *)
+
 (** {3 Build formulas from non-formulas} *)
 
 val ttrue : t

infer/src/pulse/unit/PulseFormulaTest.ml

@@ -12,12 +12,6 @@ module Formula = PulseFormula
 
 let%test_module _ =
   ( module struct
-    let normalize phi = Formula.normalize phi |> F.printf "%a" Formula.pp
-
-    let simplify ~keep phi =
-      Formula.simplify ~keep:(AbstractValue.Set.of_list keep) phi |> F.printf "%a" Formula.pp
-
-
     (** shorthand for defining formulas easily *)
 
     let i i = Formula.Term.of_intlit (IntLit.of_int i)
@@ -32,31 +26,59 @@ let%test_module _ =
 
     let ( && ) phi1 phi2 = Formula.aand phi1 phi2
 
-    let x_var = AbstractValue.mk_fresh ()
+    let var_names = Caml.Hashtbl.create 4
+
+    let mk_var name =
+      let v = AbstractValue.mk_fresh () in
+      Caml.Hashtbl.add var_names v name ;
+      v
+
+
+    let x_var = mk_var "x"
 
     let x = Formula.Term.of_absval x_var
 
-    let y_var = AbstractValue.mk_fresh ()
+    let y_var = mk_var "y"
 
     let y = Formula.Term.of_absval y_var
 
-    let z_var = AbstractValue.mk_fresh ()
+    let z_var = mk_var "z"
 
     let z = Formula.Term.of_absval z_var
 
-    let w = Formula.Term.of_absval (AbstractValue.mk_fresh ())
+    let w = Formula.Term.of_absval (mk_var "w")
+
+    let v = Formula.Term.of_absval (mk_var "v")
+
+    (** utilities for writing tests *)
+
+    let pp_var fmt v =
+      match Caml.Hashtbl.find_opt var_names v with
+      | Some name ->
+          F.pp_print_string fmt name
+      | None ->
+          AbstractValue.pp fmt v
+
+
+    let formula_pp = Formula.pp_with_pp_var pp_var
+
+    let normalize phi = Formula.normalize phi |> F.printf "%a" formula_pp
+
+    let simplify ~keep phi =
+      Formula.simplify ~keep:(AbstractValue.Set.of_list keep) phi |> F.printf "%a" formula_pp
+
 
-    let v = Formula.Term.of_absval (AbstractValue.mk_fresh ())
+    (** the actual tests *)
 
     let%expect_test _ =
       normalize (x + i 1 - i 1 < x) ;
       [%expect {|
-        [true && {(v1+1)+(-1) < v1}]|}]
+        [true && {(x+1)+(-1) < x}]|}]
 
     let%expect_test _ =
       normalize (x + (y - x) < y) ;
       [%expect {|
-        [true && {v1+(v2-v1) < v2}]|}]
+        [true && {x+(y-x) < y}]|}]
 
     let%expect_test _ =
       normalize (x = y && y = z && z = i 0 && x = i 1) ;
@@ -67,36 +89,36 @@ let%test_module _ =
     let%expect_test _ =
       normalize (x = w + y + i 1 && y + i 1 = z && x = i 1 && w + z = i 0) ;
       [%expect {|
-[0=(v4+v3) ∧ 1=v1=((v4+v2)+1) ∧ v3=(v2+1) && true]|}]
+[0=(w+z) ∧ 1=x=((w+y)+1) ∧ z=(y+1) && true]|}]
 
     let%expect_test _ =
-      normalize (x = i 0 && Formula.Term.of_binop Ne x y = i 0 && y = i 1) ;
+      normalize (Formula.Term.of_binop Ne x y = i 0 && x = i 0 && y = i 1) ;
       [%expect {|
-        [0=v1=(0≠v2) ∧ 1=v2 && true]|}]
+        [0=x=(x≠y) ∧ 1=y && true]|}]
 
     let%expect_test _ =
-      normalize (x = i 0 && Formula.Term.of_binop Eq x y = i 0 && y = i 1) ;
+      normalize (Formula.Term.of_binop Eq x y = i 0 && x = i 0 && y = i 1) ;
       [%expect {|
-        [0=v1=(0=v2) ∧ 1=v2 && true]|}]
+        [0=x=(x=y) ∧ 1=y && true]|}]
 
     let%expect_test _ =
       simplify ~keep:[x_var] (x = i 0 && y = i 1 && z = i 2 && w = i 3) ;
       [%expect {|
-[0=v1 ∧ 1=v2 ∧ 2=v3 ∧ 3=v4 && true]|}]
+[0=x ∧ 1=y ∧ 2=z ∧ 3=w && true]|}]
 
     let%expect_test _ =
       simplify ~keep:[x_var] (x = y + i 1 && x = i 0) ;
       [%expect {|
-[0=v1=(v2+1) && true]|}]
+[0=x=(y+1) && true]|}]
 
     let%expect_test _ =
       simplify ~keep:[y_var] (x = y + i 1 && x = i 0) ;
       [%expect {|
-[0=v1=(v2+1) && true]|}]
+[0=x=(y+1) && true]|}]
 
     (* should keep most of this or realize that [w = z] hence this boils down to [z+1 = 0] *)
     let%expect_test _ =
       simplify ~keep:[y_var; z_var] (x = y + z && w = x - y && v = w + i 1 && v = i 0) ;
       [%expect {|
-[0=v5=(v4+1) ∧ v1=(v2+v3) ∧ v4=(v1-v2) && true]|}]
+[0=v=(w+1) ∧ x=(y+z) ∧ w=(x-y) && true]|}]
   end )