From e35b26ae8ee3fb8e5d55a7fb26012a0e18a0d4a7 Mon Sep 17 00:00:00 2001
From: Sungkeun Cho <scho@fb.com>
Date: Wed, 11 Mar 2020 06:09:33 -0700
Subject: [PATCH] [inferbo] Get static final array values from class
 initializer

Reviewed By: ezgicicek

Differential Revision: D20383941

fbshipit-source-id: 0539673f9
---
 .../src/bufferoverrun/bufferOverrunAnalysis.ml | 18 ++++++++++--------
 .../reverse_analysis_callgraph.dot             |  5 +----
 .../codetoanalyze/java/performance/Array.java  |  6 ++++++
 3 files changed, 17 insertions(+), 12 deletions(-)

diff --git a/infer/src/bufferoverrun/bufferOverrunAnalysis.ml b/infer/src/bufferoverrun/bufferOverrunAnalysis.ml
index 7e098d19f..7a8ba2333 100644
--- a/infer/src/bufferoverrun/bufferOverrunAnalysis.ml
+++ b/infer/src/bufferoverrun/bufferOverrunAnalysis.ml
@@ -234,16 +234,18 @@ module TransferFunctions = struct
     fun tenv get_summary exp mem ->
       Option.value_map (Exp.get_java_class_initializer tenv exp) ~default:mem
         ~f:(fun (clinit_pname, pvar, fn, field_typ) ->
+          let copy_from_class_init () =
+            Option.value_map (get_summary clinit_pname) ~default:mem ~f:(fun clinit_mem ->
+                let field_loc = Loc.append_field ~typ:field_typ (Loc.of_pvar pvar) ~fn in
+                copy_reachable_locs_from field_loc ~from_mem:clinit_mem ~to_mem:mem )
+          in
           match field_typ.Typ.desc with
-          | Typ.Tptr ({desc= Tstruct _}, _) ->
+          | Typ.Tptr ({desc= Tstruct _}, _) when is_known_java_static_field fn ->
               (* It copies all of the reachable values when the contents of the field are commonly
-                 used as immutable, e.g., values of enum.  Otherwise, it copies only the size of
-                 static final array. *)
-              Option.value_map (get_summary clinit_pname) ~default:mem ~f:(fun clinit_mem ->
-                  let field_loc = Loc.append_field ~typ:field_typ (Loc.of_pvar pvar) ~fn in
-                  if is_known_java_static_field fn then
-                    copy_reachable_locs_from field_loc ~from_mem:clinit_mem ~to_mem:mem
-                  else mem )
+                 used as immutable, e.g., values of enum. *)
+              copy_from_class_init ()
+          | Typ.Tptr ({desc= Tarray _}, _) ->
+              copy_from_class_init ()
           | _ ->
               mem )
 
diff --git a/infer/tests/build_systems/incremental_analysis_cost_change/reverse_analysis_callgraph.dot b/infer/tests/build_systems/incremental_analysis_cost_change/reverse_analysis_callgraph.dot
index 4b60ff8cc..9f6ca4302 100644
--- a/infer/tests/build_systems/incremental_analysis_cost_change/reverse_analysis_callgraph.dot
+++ b/infer/tests/build_systems/incremental_analysis_cost_change/reverse_analysis_callgraph.dot
@@ -20,10 +20,7 @@ digraph callgraph {
   N2 -> N4 ;
   N2 -> N3 ;
 
-  N9 [ label = "void PrintStream.println(String)", flag = false ];
-  N9 -> N2 ;
-
-  N8 [ label = "void System.<clinit>()", flag = false ];
+  N8 [ label = "void PrintStream.println(String)", flag = false ];
   N8 -> N2 ;
 
   N3 [ label = "void Test.complexityDecrease(int)", flag = true ];
diff --git a/infer/tests/codetoanalyze/java/performance/Array.java b/infer/tests/codetoanalyze/java/performance/Array.java
index 3163beea6..de7b6edd6 100644
--- a/infer/tests/codetoanalyze/java/performance/Array.java
+++ b/infer/tests/codetoanalyze/java/performance/Array.java
@@ -91,4 +91,10 @@ public class Array {
   void toArray_linear(java.util.ArrayList<String> list) {
     for (int i = 0; i < list.toArray().length; i++) {}
   }
+
+  private static final String[] static_final_field = new String[] {"", ""};
+
+  void use_static_final_array_field_constant() {
+    for (int i = 0; i < static_final_field.length; i++) {}
+  }
 }