[cost] Remove dead field Struct.subs

Summary:
This diff removes a dead field `Struct.subs`, which was used in
heuristics finding methods from sub-classes.

Reviewed By: ezgicicek

Differential Revision: D22945346

fbshipit-source-id: 4b3bf0093

infer/src/IR/Struct.ml

@@ -43,7 +43,6 @@ type t =
   { fields: fields  (** non-static fields *)
   ; statics: fields  (** static fields *)
   ; supers: Typ.Name.t list  (** superclasses *)
-  ; subs: Typ.Name.Set.t  (** subclasses, initialized after merging type environments *)
   ; methods: Procname.t list  (** methods defined *)
   ; exported_objc_methods: Procname.t list  (** methods in ObjC interface, subset of [methods] *)
   ; annots: Annot.Item.t  (** annotations *)
@@ -58,7 +57,7 @@ let pp_field pe f (field_name, typ, ann) =
 
 
 let pp pe name f
-    ({fields; statics; subs; supers; methods; exported_objc_methods; annots; java_class_info; dummy}[@warning
+    ({fields; statics; supers; methods; exported_objc_methods; annots; java_class_info; dummy}[@warning
                                                                                                 "+9"])
     =
   let pp_field pe f (field_name, typ, ann) =
@@ -76,7 +75,6 @@ let pp pe name f
      @[<v>fields: {@[<v>%a@]}@,\
      statics: {@[<v>%a@]}@,\
      supers: {@[<v>%a@]}@,\
-     subs: {@[<v>%a@]}@,\
      methods: {@[<v>%a@]}@,\
      exported_obj_methods: {@[<v>%a@]}@,\
      annots: {@[<v>%a@]}@,\
@@ -89,8 +87,6 @@ let pp pe name f
     statics
     (seq (fun f n -> F.fprintf f "@;<0 2>%a" Typ.Name.pp n))
     supers
-    (seq (fun f n -> F.fprintf f "@;<0 2>%a" Typ.Name.pp n))
-    (Typ.Name.Set.elements subs)
     (seq (fun f m -> F.fprintf f "@;<0 2>%a" Procname.pp m))
     methods
     (seq (fun f m -> F.fprintf f "@;<0 2>%a" Procname.pp m))
@@ -105,16 +101,14 @@ let internal_mk_struct ?default ?fields ?statics ?methods ?exported_objc_methods
     ; methods= []
     ; exported_objc_methods= []
     ; supers= []
-    ; subs= Typ.Name.Set.empty
     ; annots= Annot.Item.empty
     ; java_class_info= None
     ; dummy= false }
   in
   let mk_struct_ ?(default = default_) ?(fields = default.fields) ?(statics = default.statics)
       ?(methods = default.methods) ?(exported_objc_methods = default.exported_objc_methods)
-      ?(supers = default.supers) ?(subs = default.subs) ?(annots = default.annots)
+      ?(supers = default.supers) ?(annots = default.annots) ?(dummy = default.dummy) () =
-      ?(dummy = default.dummy) () =
+    {fields; statics; methods; exported_objc_methods; supers; annots; java_class_info; dummy}
-    {fields; statics; methods; exported_objc_methods; supers; subs; annots; java_class_info; dummy}
   in
   mk_struct_ ?default ?fields ?statics ?methods ?exported_objc_methods ?supers ?annots ?dummy ()
 
@@ -188,8 +182,6 @@ let get_field_type_and_annotation ~lookup field_name_to_lookup typ =
 
 let is_dummy {dummy} = dummy
 
-let add_sub sub x = {x with subs= Typ.Name.Set.add sub x.subs}
-
 let merge_lists ~compare ~newer ~current =
   let equal x y = Int.equal 0 (compare x y) in
   match (newer, current) with

infer/src/IR/Struct.mli

@@ -26,7 +26,6 @@ type t =
   { fields: fields  (** non-static fields *)
   ; statics: fields  (** static fields *)
   ; supers: Typ.Name.t list  (** superclasses *)
-  ; subs: Typ.Name.Set.t  (** subclasses, initialized after merging type environments *)
   ; methods: Procname.t list  (** methods defined *)
   ; exported_objc_methods: Procname.t list  (** methods in ObjC interface, subset of [methods] *)
   ; annots: Annot.Item.t  (** annotations *)
@@ -70,9 +69,6 @@ val get_field_type_and_annotation :
   lookup:lookup -> Fieldname.t -> Typ.t -> (Typ.t * Annot.Item.t) option
 (** Return the type of the field [fn] and its annotation, None if [typ] has no field named [fn] *)
 
-val add_sub : Typ.Name.t -> t -> t
-(** Add a subclass to the struct type *)
-
 val merge : Typ.Name.t -> newer:t -> current:t -> t
 (** best effort directed merge of two structs for the same typename *)
 

infer/src/IR/Tenv.ml

@@ -171,19 +171,6 @@ let store_to_filename tenv tenv_filename =
   if Config.debug_mode then store_debug_file tenv tenv_filename
 
 
-let init_inheritances tenv =
-  let sub_to_supers =
-    TypenameHash.fold (fun sub {Struct.supers} acc -> (sub, supers) :: acc) tenv []
-  in
-  List.iter sub_to_supers ~f:(fun (sub, supers) ->
-      List.iter supers ~f:(fun super ->
-          (* Ignore the super class of java.lang.Object since its sub-classes are too many, which
-             harms the analysis precision. *)
-          if not (Typ.Name.equal super Typ.Name.Java.java_lang_object) then
-            Option.iter (lookup tenv super) ~f:(fun super_struct ->
-                Struct.add_sub sub super_struct |> TypenameHash.replace tenv super ) ) )
-
-
 let store_global tenv =
   (* update in-memory global tenv for later uses by this process, e.g. in single-core mode the
      frontend and backend run in the same process *)
@@ -192,7 +179,6 @@ let store_global tenv =
   let tenv = TypenameHashNormalizer.normalize tenv in
   L.debug Capture Quiet "Tenv.store: canonicalized tenv has size %d bytes.@."
     (Obj.(reachable_words (repr tenv)) * (Sys.word_size / 8)) ;
-  init_inheritances tenv ;
   global_tenv := Some tenv ;
   store_to_filename tenv global_tenv_path
 

infer/tests/codetoanalyze/java/performance/InheritanceTest.java

@@ -40,7 +40,7 @@ class InheritanceTest {
     public void foo(int x) {}
   }
 
-  /* By heuristics, [Impl1.foo] is selected. It is hard to say good or bad. */
+  /* As of now, we cannot find implementations of interface methods. */
   public void call_interface_method2_linear_FN(MyInterface2 c, int x) {
     c.foo(x);
   }