[biabd] kill Config.undo_join

Summary:
This was hardcoded to `true` and its purpose is unclear to me. I kill
what confuses me.

Reviewed By: jeremydubreil

Differential Revision: D15294783

fbshipit-source-id: 3c1c469ee

infer/src/base/Config.ml

@@ -273,9 +273,6 @@ let starvation_issues_dir_name = "starvation_issues"
 (** Enable detailed tracing information during array abstraction *)
 let trace_absarray = false
 
-(** If true, optimize based on locality using reachability *)
-let undo_join = true
-
 let unsafe_unret = "<\"Unsafe_unretained\">"
 
 let weak = "<\"Weak\">"

infer/src/base/Config.mli

@@ -189,8 +189,6 @@ val trace_absarray : bool
 
 val trace_events_file : string
 
-val undo_join : bool
-
 val unsafe_unret : string
 
 val use_cost_threshold : bool

infer/src/biabduction/interproc.ml

@@ -890,9 +890,7 @@ let perform_analysis_phase exe_env tenv (summary : Summary.t) (proc_cfg : ProcCf
         (match speco with None -> () | Some spec -> valid_specs := !valid_specs @ [spec]) ;
         speco
       in
-      if Config.undo_join then
-        ignore (BiabductionSummary.Jprop.filter filter candidate_preconditions)
-      else ignore (List.map ~f:filter candidate_preconditions)
+      ignore (BiabductionSummary.Jprop.filter filter candidate_preconditions)
     in
     let get_results () =
       let specs = !valid_specs in