[ConfigImpact] Use cost analysis to determine cheapness

Summary:
Reporting all ungated (un configed?) function calls causes many FPs. Instead, we rely on complexity analysis to determine whether a function is cheap/expensive: if the callee's complexity is not symbolic (e.g. constant), we consider it as cheap and don't keep track of it.

Note that we don't take the instantiated/modeled cost into account yet. So, if we have  `foo(int n)` with complexity `O(n)`, and call it as `foo(3)`, we would still keep track of it. Similarly, if `foo` is a modeled function with constant time complexity, we would have no summary for it hence would keep track of it.

These will be improved later.

Reviewed By: skcho

Differential Revision: D27430485

fbshipit-source-id: d5f66320d

infer/src/backend/registerCheckers.ml

@@ -194,7 +194,8 @@ let all_checkers =
   ; { checker= ConfigImpactAnalysis
     ; callbacks=
         (let checker =
-           interprocedural Payloads.Fields.config_impact_analysis ConfigImpactAnalysis.checker
+           interprocedural2 Payloads.Fields.config_impact_analysis Payloads.Fields.cost
+             ConfigImpactAnalysis.checker
          in
          [(checker, Clang); (checker, Java)] ) } ]
 

infer/src/base/Checker.ml

@@ -156,7 +156,7 @@ let config_unsafe checker =
           "[EXPERIMENTAL] Collects function that are called without config checks."
       ; cli_flags= Some {deprecated= []; show_in_help= true}
       ; enabled_by_default= false
-      ; activates= [] }
+      ; activates= [Cost] }
   | Cost ->
       { id= "cost"
       ; kind=

infer/src/cost/ConfigImpactAnalysis.ml

@@ -250,7 +250,7 @@ module Dom = struct
     ; config_fields= Fields.widen ~prev:prev.config_fields ~next:next.config_fields ~num_iters }
 
 
-  let to_summary has_call_stmt {unchecked_callees; unchecked_callees_cond; config_fields} =
+  let to_summary ~has_call_stmt {unchecked_callees; unchecked_callees_cond; config_fields} =
     {Summary.unchecked_callees; unchecked_callees_cond; has_call_stmt; config_fields}
 
 
@@ -327,13 +327,24 @@ module Dom = struct
   let call analyze_dependency callee location
       ({config_checks; field_checks; unchecked_callees; unchecked_callees_cond} as astate) =
     if ConfigChecks.is_top config_checks then
+      let callee_summary = analyze_dependency callee in
+      if
+        Option.exists callee_summary ~f:(fun (_, (_, (cost_summary : CostDomain.summary option))) ->
+            Option.exists cost_summary ~f:(fun (cost_summary : CostDomain.summary) ->
+                let callee_cost = CostDomain.get_operation_cost cost_summary.post in
+                not (CostDomain.BasicCost.is_symbolic callee_cost.cost) ) )
+      then (* If callee is cheap by heuristics, ignore it. *)
+        astate
+      else
         let new_unchecked_callees, new_unchecked_callees_cond =
-        match analyze_dependency callee with
+          match callee_summary with
           | Some
               ( _
-            , { Summary.unchecked_callees= callee_summary
+              , ( Some
+                    { Summary.unchecked_callees= callee_summary
                     ; unchecked_callees_cond= callee_summary_cond
-              ; has_call_stmt } )
+                    ; has_call_stmt }
+                , _callee_cost_summary ) )
             when has_call_stmt ->
               (* If callee's summary is not leaf, use it. *)
               ( UncheckedCallees.replace_location_by_call location callee_summary
@@ -368,7 +379,7 @@ module TransferFunctions = struct
   module CFG = ProcCfg.Normal
   module Domain = Dom
 
-  type analysis_data = Summary.t InterproceduralAnalysis.t
+  type analysis_data = (Summary.t option * CostDomain.summary option) InterproceduralAnalysis.t
 
   let is_java_boolean_value_method pname =
     Procname.get_class_name pname |> Option.exists ~f:(String.equal "java.lang.Boolean")
@@ -460,4 +471,4 @@ let has_call_stmt proc_desc =
 let checker ({InterproceduralAnalysis.proc_desc} as analysis_data) =
   Option.map (Analyzer.compute_post analysis_data ~initial:Dom.init proc_desc) ~f:(fun astate ->
       let has_call_stmt = has_call_stmt proc_desc in
-      Dom.to_summary has_call_stmt astate )
+      Dom.to_summary ~has_call_stmt astate )

infer/src/cost/ConfigImpactAnalysis.mli

@@ -39,4 +39,5 @@ module Summary : sig
   val instantiate_unchecked_callees_cond : all_config_fields:Fields.t -> t -> t
 end
 
-val checker : Summary.t InterproceduralAnalysis.t -> Summary.t option
+val checker :
+  (Summary.t option * CostDomain.summary option) InterproceduralAnalysis.t -> Summary.t option