3 files changed, 37 insertions, 1 deletions
diff --git a/src/CfimAst.ml b/src/CfimAst.ml
index 250cd223..28f23758 100644
--- a/src/CfimAst.ml
+++ b/src/CfimAst.ml
@@ -5,6 +5,8 @@ open Expressions
 
 module FunDefId = IdGen ()
 
+module RegionGroupId = IdGen ()
+
 type var = {
   index : VarId.id;  (** Unique variable identifier *)
   name : string option;
@@ -24,9 +26,26 @@ type fun_id = Local of FunDefId.id | Assumed of assumed_fun_id
 
 type assertion = { cond : operand; expected : bool } [@@deriving show]
 
+type region_group = {
+  id : RegionGroupId.id;
+  regions : RegionVarId.id list;
+  parents : RegionGroupId.id list;
+}
+[@@deriving show]
+(** A group of regions.
+
+    Results from a lifetime analysis: we group the regions with the same
+    lifetime together, and compute the hierarchy between the regions.
+    This is necessary to introduce the proper abstraction with the
+    proper constraints, when evaluating a function call in symbolic mode.
+*)
+
+type region_groups = region_group list [@@deriving show]
+
 type fun_sig = {
   region_params : region_var list;
   num_early_bound_regions : int;
+  regions_hierarchy : region_groups;
   type_params : type_var list;
   inputs : sty list;
   output : sty;
diff --git a/src/CfimOfJson.ml b/src/CfimOfJson.ml
index 3494f004..4f39d7ff 100644
--- a/src/CfimOfJson.ml
+++ b/src/CfimOfJson.ml
@@ -436,6 +436,20 @@ let assertion_of_json (js : json) : (A.assertion, string) result =
         Ok { A.cond; expected }
     | _ -> Error "")
 
+let region_group_of_json (js : json) : (A.region_group, string) result =
+  combine_error_msgs js "region_group_of_json"
+    (match js with
+    | `Assoc [ ("id", id); ("regions", regions); ("parents", parents) ] ->
+        let* id = A.RegionGroupId.id_of_json id in
+        let* regions = list_of_json T.RegionVarId.id_of_json regions in
+        let* parents = list_of_json A.RegionGroupId.id_of_json parents in
+        Ok { A.id; regions; parents }
+    | _ -> Error "")
+
+let region_groups_of_json (js : json) : (A.region_groups, string) result =
+  combine_error_msgs js "region_group_of_json"
+    (list_of_json region_group_of_json js)
+
 let fun_sig_of_json (js : json) : (A.fun_sig, string) result =
   combine_error_msgs js "fun_sig_of_json"
     (match js with
@@ -443,12 +457,14 @@ let fun_sig_of_json (js : json) : (A.fun_sig, string) result =
         [
           ("region_params", region_params);
           ("num_early_bound_regions", num_early_bound_regions);
+          ("regions_hierarchy", regions_hierarchy);
           ("type_params", type_params);
           ("inputs", inputs);
           ("output", output);
         ] ->
         let* region_params = list_of_json region_var_of_json region_params in
         let* num_early_bound_regions = int_of_json num_early_bound_regions in
+        let* regions_hierarchy = region_groups_of_json regions_hierarchy in
         let* type_params = list_of_json type_var_of_json type_params in
         let* inputs = list_of_json sty_of_json inputs in
         let* output = sty_of_json output in
@@ -456,6 +472,7 @@ let fun_sig_of_json (js : json) : (A.fun_sig, string) result =
           {
             A.region_params;
             num_early_bound_regions;
+            regions_hierarchy;
             type_params;
             inputs;
             output;
diff --git a/tests/trace_reference.txt b/tests/trace_reference.txt
index 52edcc93..f32f5de8 100644
--- a/tests/trace_reference.txt
+++ b/tests/trace_reference.txt
@@ -724,7 +724,7 @@ fn test_loop4(max : u32) -> u32 {
   var@18 : (u32, bool);
   var@19 : (u32, bool);
 
-  i := 0: u32
+  i := 1: u32
   j := 0: u32
   s := 0: u32
   loop {