[liveness] fix bug in usage of OneInstrPerNode CFG

Reviewed By: mbouaziz, jvillard

Differential Revision: D5468487

fbshipit-source-id: 7ab6f9a

infer/src/checkers/liveness.ml

@@ -77,11 +77,17 @@ let checker {Callbacks.tenv; summary; proc_desc} : Specs.summary =
     | _
      -> ()
   in
-  List.iter (CFG.nodes cfg) ~f:(fun node ->
-      (* note: extract_pre grabs the post, since the analysis is backward *)
-      match Analyzer.extract_pre (CFG.id node) invariant_map with
-      | Some live_vars
-       -> List.iter ~f:(report_dead_store live_vars) (CFG.instrs node)
-      | None
-       -> () ) ;
+  let report_on_node node =
+    List.iter (CFG.instr_ids node) ~f:(fun (instr, node_id_opt) ->
+        match node_id_opt with
+        | Some node_id -> (
+          match Analyzer.extract_pre node_id invariant_map with
+          | Some live_vars
+           -> report_dead_store live_vars instr
+          | None
+           -> () )
+        | None
+         -> () )
+  in
+  List.iter (CFG.nodes cfg) ~f:report_on_node ;
   summary

infer/tests/codetoanalyze/cpp/liveness/dead_stores.cpp

@@ -31,6 +31,21 @@ void dead_pointer_bad() {
   int* x = #
 }
 
+void plus_plus1_bad() {
+  int i = 0;
+  ++i;
+}
+
+void plus_plus2_bad() {
+  int i = 0;
+  i++;
+}
+
+int plus_plus3_bad() {
+  int i = 0;
+  return i++;
+}
+
 int return_ok() {
   int x = 5;
   return x;
@@ -85,6 +100,19 @@ int* assign_pointer2_ok() {
 
 void by_ref_ok(int& ref) { ref = 7; }
 
+int plus_plus_ok() {
+  int x = 0;
+  return ++x;
+}
+
+int plus_plus_loop_ok(int n) {
+  int i;
+  for (i = 0; i < n; i++) {
+    i++;
+  }
+  return i;
+}
+
 char* global;
 
 void FP_assign_array_tricky_ok() {

infer/tests/codetoanalyze/cpp/liveness/issues.exp

@@ -2,5 +2,8 @@ codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::FP_assign_array_tricky_
 codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::dead_pointer_bad, 2, DEAD_STORE, [Write of unused value]
 codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::dead_then_live_bad, 1, DEAD_STORE, [Write of unused value]
 codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::easy_bad, 0, DEAD_STORE, [Write of unused value]
+codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::plus_plus1_bad, 2, DEAD_STORE, [Write of unused value]
+codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::plus_plus2_bad, 2, DEAD_STORE, [Write of unused value]
+codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::plus_plus3_bad, 2, DEAD_STORE, [Write of unused value]
 codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::reassign_param_bad, 0, DEAD_STORE, [Write of unused value]
 codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::use_then_dead_bad, 3, DEAD_STORE, [Write of unused value]