[Perf] Emit ZERO_EXECUTION_TIME_CALL issue-type, when zero-costing functions are met

Reviewed By: ezgicicek

Differential Revision: D9195167

fbshipit-source-id: 35985c83c

infer/src/base/IssueType.ml

@@ -357,3 +357,5 @@ let untrusted_url_risk = from_string "UNTRUSTED_URL_RISK"
 let untrusted_variable_length_array = from_string "UNTRUSTED_VARIABLE_LENGTH_ARRAY"
 
 let wrong_argument_number = from_string "Wrong_argument_number" ~hum:"Wrong Argument Number"
+
+let zero_execution_time_call = from_string ~enabled:false "ZERO_EXECUTION_TIME_CALL"

infer/src/base/IssueType.mli

@@ -270,3 +270,5 @@ val untrusted_variable_length_array : t
 val user_controlled_sql_risk : t
 
 val wrong_argument_number : t
+
+val zero_execution_time_call : t

infer/src/bufferoverrun/itv.ml

@@ -368,6 +368,8 @@ module NonNegativePolynomial = struct
 
   let is_top = function Top -> true | _ -> false
 
+  let is_zero = function NonTop p when NonNegativeNonTopPolynomial.is_zero p -> true | _ -> false
+
   let top_lifted_increasing ~f p1 p2 =
     match (p1, p2) with Top, _ | _, Top -> Top | NonTop p1, NonTop p2 -> NonTop (f p1 p2)
 

infer/src/bufferoverrun/itv.mli

@@ -43,6 +43,8 @@ module NonNegativePolynomial : sig
 
   val is_top : astate -> bool
 
+  val is_zero : astate -> bool
+
   val plus : astate -> astate -> astate
 
   val mult : astate -> astate -> astate

infer/src/checkers/cost.ml

@@ -974,17 +974,24 @@ end
 
 module AnalyzerWCET = AbstractInterpreter.MakeNoCFG (InstrCFGScheduler) (TransferFunctionsWCET)
 
-let check_and_report_infinity cost proc_desc summary =
-  if BasicCost.is_top cost then
-    let loc = Procdesc.get_start_node proc_desc |> Procdesc.Node.get_loc in
-    let message =
-      F.asprintf "The execution time of the function %a cannot be computed" Typ.Procname.pp
-        (Procdesc.get_proc_name proc_desc)
-    in
-    let exn =
-      Exceptions.Checkers (IssueType.infinite_execution_time_call, Localise.verbatim_desc message)
-    in
-    Reporting.log_error ~loc ~extras:(compute_errlog_extras cost) summary exn
+let check_and_report_top_and_bottom cost proc_desc summary =
+  let message =
+    F.asprintf "The execution time of the function %a %s" Typ.Procname.pp
+      (Procdesc.get_proc_name proc_desc)
+  in
+  let exn_opt =
+    if BasicCost.is_top cost then
+      let msg = message "cannot be computed" in
+      Some
+        (Exceptions.Checkers (IssueType.infinite_execution_time_call, Localise.verbatim_desc msg))
+    else if BasicCost.is_zero cost then
+      let msg = message "is zero" in
+      Some (Exceptions.Checkers (IssueType.zero_execution_time_call, Localise.verbatim_desc msg))
+    else None
+  in
+  let loc () = Procdesc.get_start_node proc_desc |> Procdesc.Node.get_loc in
+  Option.iter exn_opt
+    ~f:(Reporting.log_error ~loc:(loc ()) ~extras:(compute_errlog_extras cost) summary)
 
 
 let checker ({Callbacks.tenv; proc_desc} as callback_args) : Summary.t =
@@ -1068,7 +1075,7 @@ let checker ({Callbacks.tenv; proc_desc} as callback_args) : Summary.t =
         (Procdesc.get_proc_name proc_desc)
         (Container.length ~fold:NodeCFG.fold_nodes node_cfg)
         pp_extra BasicCost.pp exit_cost ;
-      check_and_report_infinity exit_cost proc_desc summary ;
+      check_and_report_top_and_bottom exit_cost proc_desc summary ;
       Payload.update_summary {post= exit_cost} summary
   | None ->
       if Procdesc.Node.get_succs (Procdesc.get_start_node proc_desc) <> [] then (

infer/tests/codetoanalyze/c/performance/cost_test.c

@@ -126,3 +126,5 @@ void call_while_upto20_minus100_bad() { while_upto20_bad(-100); }
 void call_while_upto20_10_good() { while_upto20_bad(10); }
 
 void call_while_upto20_unsigned_good(unsigned x) { while_upto20_bad(x); }
+
+void zero_cost_function() {}

infer/tests/codetoanalyze/c/performance/issues.exp

@@ -46,6 +46,7 @@ codetoanalyze/c/performance/cost_test.c, main_bad, 8, EXPENSIVE_EXECUTION_TIME_C
 codetoanalyze/c/performance/cost_test.c, while_upto20_bad, 1, EXPENSIVE_EXECUTION_TIME_CALL, no_bucket, ERROR, [with estimated cost 1 + 5 * (-m.lb + 20), degree = 1]
 codetoanalyze/c/performance/cost_test.c, while_upto20_bad, 2, EXPENSIVE_EXECUTION_TIME_CALL, no_bucket, ERROR, [with estimated cost 1 + 5 * (-m.lb + 20), degree = 1]
 codetoanalyze/c/performance/cost_test.c, while_upto20_bad, 5, EXPENSIVE_EXECUTION_TIME_CALL, no_bucket, ERROR, [with estimated cost 3 + 5 * (-m.lb + 20), degree = 1]
+codetoanalyze/c/performance/cost_test.c, zero_cost_function, 0, ZERO_EXECUTION_TIME_CALL, no_bucket, ERROR, []
 codetoanalyze/c/performance/cost_test_deps.c, if_bad_loop, 12, EXPENSIVE_EXECUTION_TIME_CALL, no_bucket, ERROR, [with estimated cost 201, degree = 0]
 codetoanalyze/c/performance/cost_test_deps.c, loop_despite_inferbo, 3, EXPENSIVE_EXECUTION_TIME_CALL, no_bucket, ERROR, [with estimated cost 1204, degree = 0]
 codetoanalyze/c/performance/cost_test_deps.c, loop_despite_inferbo, 3, EXPENSIVE_EXECUTION_TIME_CALL, no_bucket, ERROR, [with estimated cost 1204, degree = 0]

infer/tests/codetoanalyze/java/performance/Cost_test.java

@@ -116,4 +116,7 @@ public class Cost_test {
     k4 = bar_OK() + foo_OK() + cond_OK(19) * 3;
     return 0;
   }
+
+  // Cost: 0
+  private static void zeroCostFunction() {}
 }

infer/tests/codetoanalyze/java/performance/issues.exp

@@ -48,6 +48,7 @@ codetoanalyze/java/performance/Cost_test.java, int Cost_test.loop3(int), 2, EXPE
 codetoanalyze/java/performance/Cost_test.java, int Cost_test.main_bad(), 8, EXPENSIVE_EXECUTION_TIME_CALL, no_bucket, ERROR, [with estimated cost 237, degree = 0]
 codetoanalyze/java/performance/Cost_test.java, int Cost_test.main_bad(), 8, EXPENSIVE_EXECUTION_TIME_CALL, no_bucket, ERROR, [with estimated cost 205, degree = 0]
 codetoanalyze/java/performance/Cost_test.java, int Cost_test.main_bad(), 9, EXPENSIVE_EXECUTION_TIME_CALL, no_bucket, ERROR, [with estimated cost 243, degree = 0]
+codetoanalyze/java/performance/Cost_test.java, void Cost_test.zeroCostFunction(), 0, ZERO_EXECUTION_TIME_CALL, no_bucket, ERROR, []
 codetoanalyze/java/performance/Cost_test_deps.java, int Cost_test_deps.if_bad_loop(), 12, EXPENSIVE_EXECUTION_TIME_CALL, no_bucket, ERROR, [with estimated cost 201, degree = 0]
 codetoanalyze/java/performance/Cost_test_deps.java, int Cost_test_deps.loop_despite_inferbo(int), 3, EXPENSIVE_EXECUTION_TIME_CALL, no_bucket, ERROR, [with estimated cost 1303, degree = 0]
 codetoanalyze/java/performance/Cost_test_deps.java, int Cost_test_deps.loop_despite_inferbo(int), 3, EXPENSIVE_EXECUTION_TIME_CALL, no_bucket, ERROR, [with estimated cost 1302, degree = 0]