diff --git a/headers/header_spec.txt b/headers/header_spec.txt
index d1b383e76b2d8a39234b67339deb1984c7ad12b3..e2e986a8d06daad516d7df60b2c8be08e78d9da3 100644
--- a/headers/header_spec.txt
+++ b/headers/header_spec.txt
@@ -1674,6 +1674,8 @@ src/plugins/wp/WpTac.ml: CEA_WP
src/plugins/wp/WpTac.mli: CEA_WP
src/plugins/wp/calculus.ml: CEA_WP
src/plugins/wp/calculus.mli: CEA_WP
+src/plugins/wp/wpCalculus: CEA_WP
+src/plugins/wp/wpCalculus.mli: CEA_WP
src/plugins/wp/cfgDump.ml: CEA_WP
src/plugins/wp/cfgDump.mli: CEA_WP
src/plugins/wp/cfgWP.ml: CEA_WP
diff --git a/src/plugins/wp/Makefile.in b/src/plugins/wp/Makefile.in
index e5d999ad78ced57995df786b11a3bbc8dbdd8f66..3647977959eaf85718b9198d1647a4149774ea7c 100644
--- a/src/plugins/wp/Makefile.in
+++ b/src/plugins/wp/Makefile.in
@@ -97,7 +97,7 @@ PLUGIN_CMO:= \
filter_axioms Cache ProverWhy3 \
driver prover ProverSearch ProverScript \
Generator Factory \
- calculus cfgDump cfgWP \
+ calculus cfgCalculus cfgDump cfgWP \
register VC
PLUGIN_CMI:=
diff --git a/src/plugins/wp/cfgCalculus.ml b/src/plugins/wp/cfgCalculus.ml
new file mode 100644
index 0000000000000000000000000000000000000000..68dccb3784907a9663090a404fdee8f4e4bb71d3
--- /dev/null
+++ b/src/plugins/wp/cfgCalculus.ml
@@ -0,0 +1,134 @@
+(**************************************************************************)
+(* *)
+(* This file is part of WP plug-in of Frama-C. *)
+(* *)
+(* Copyright (C) 2007-2020 *)
+(* CEA (Commissariat a l'energie atomique et aux energies *)
+(* alternatives) *)
+(* *)
+(* you can redistribute it and/or modify it under the terms of the GNU *)
+(* Lesser General Public License as published by the Free Software *)
+(* Foundation, version 2.1. *)
+(* *)
+(* It is distributed in the hope that it will be useful, *)
+(* but WITHOUT ANY WARRANTY; without even the implied warranty of *)
+(* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *)
+(* GNU Lesser General Public License for more details. *)
+(* *)
+(* See the GNU Lesser General Public License version 2.1 *)
+(* for more details (enclosed in the file licenses/LGPLv2.1). *)
+(* *)
+(**************************************************************************)
+
+open Cil_types
+open Cil_datatype
+
+(* -------------------------------------------------------------------------- *)
+(* --- Automata Helpers --- *)
+(* -------------------------------------------------------------------------- *)
+
+module Cfg = Interpreted_automata
+module G = Cfg.G
+module V = Cfg.Vertex
+module Vhash = V.Hashtbl
+type vertex = Cfg.vertex
+
+(* -------------------------------------------------------------------------- *)
+(* --- WP Calculus Driver from Interpreted Automata --- *)
+(* -------------------------------------------------------------------------- *)
+
+module Make(M : Mcfg.S) =
+struct
+
+ type env = {
+ kf: kernel_function;
+ mutable ki: kinstr; (* Current localisation *)
+ cfg: Cfg.automaton;
+ we: M.t_env;
+ wp: M.t_prop option Vhash.t; (* None is used for non-dag detection *)
+ }
+
+ let fmerge env f = function
+ | [] -> M.empty
+ | [x] -> f x
+ | x::xs ->
+ let cup = M.merge env.we in
+ List.fold_left (fun p y -> cup (f y) p) (f x) xs
+
+ let succ env a = G.succ_e env.cfg.graph a
+
+ exception NonNaturalLoop of kernel_function * kinstr
+
+ let rec wp (env:env) (a:vertex) : M.t_prop =
+ match Vhash.find env.wp a with
+ | None -> raise (NonNaturalLoop(env.kf,env.ki))
+ | Some pi -> pi
+ | exception Not_found ->
+ (* cut circularities *)
+ Vhash.add env.wp a None ;
+ let pi = match a.vertex_start_of with
+ | None -> transitions env a
+ | Some s -> stmt env a s
+ in Vhash.add env.wp a (Some pi) ; pi
+
+ (* Compute a stmt node *)
+ and stmt env a (s: stmt) : M.t_prop =
+ let ki = env.ki in
+ let kl = Cil.CurrentLoc.get () in
+ try
+ env.ki <- Kstmt s ;
+ Cil.CurrentLoc.set (Stmt.loc s) ;
+ let pi = M.label env.we (Some s) (Clabels.stmt s) (annots env a s) in
+ Cil.CurrentLoc.set kl ;
+ env.ki <- ki ; pi
+ with err ->
+ Cil.CurrentLoc.set kl ;
+ env.ki <- ki ; raise err
+
+ (* Consider annotations *)
+ and annots env a (s: stmt) : M.t_prop =
+ (*TODO: apply code annots *) branching env a s
+
+ (* Branching wrt control-flow *)
+ and branching env a (_: stmt) : M.t_prop =
+ (*TODO: apply conditional & switches *)
+ transitions env a
+
+ (* Merge all successors *)
+ and transitions env a : M.t_prop =
+ fmerge env (transition env) (succ env a)
+
+ (* Compute a single transition *)
+ and transition env (_,edge,dst) : M.t_prop =
+ let p = wp env dst in
+ match edge.edge_transition with
+ | Skip -> wp env dst
+ | Return(r,s) -> M.return env.we s r p
+ | Enter { blocals=xs } -> M.scope env.we xs SC_Block_in p
+ | Leave { blocals=xs } -> M.scope env.we xs SC_Block_out p
+ | Instr (i,s) -> instr env s i p
+ | Prop _ | Guard _ -> (* soundly ignored *) p
+
+ (* Compute a single instruction *)
+ and instr env stmt instr p =
+ match instr with
+ | Skip _ | Code_annot _ -> p
+ | Set(lv,e,_) -> M.assign env.we stmt lv e p
+ | Local_init(x,AssignInit i,_) -> M.init env.we x (Some i) p
+ | Local_init(_,ConsInit _,_) -> (* soundly ignored *) p
+ | Call _ -> assert false
+ | Asm _ -> assert false
+
+ (* Putting everything together *)
+ let compute kf =
+ let env = {
+ kf ; ki = Kglobal ;
+ cfg = Cfg.get_automaton kf ;
+ we = M.new_env kf ;
+ wp = Vhash.create 32 ;
+ } in
+ env.we , wp env env.cfg.entry_point
+
+end
+
+(* -------------------------------------------------------------------------- *)
diff --git a/src/plugins/wp/cfgCalculus.mli b/src/plugins/wp/cfgCalculus.mli
new file mode 100644
index 0000000000000000000000000000000000000000..696f80f41740a349a759aaf04c1e4cf499ce6f94
--- /dev/null
+++ b/src/plugins/wp/cfgCalculus.mli
@@ -0,0 +1,34 @@
+(**************************************************************************)
+(* *)
+(* This file is part of WP plug-in of Frama-C. *)
+(* *)
+(* Copyright (C) 2007-2020 *)
+(* CEA (Commissariat a l'energie atomique et aux energies *)
+(* alternatives) *)
+(* *)
+(* you can redistribute it and/or modify it under the terms of the GNU *)
+(* Lesser General Public License as published by the Free Software *)
+(* Foundation, version 2.1. *)
+(* *)
+(* It is distributed in the hope that it will be useful, *)
+(* but WITHOUT ANY WARRANTY; without even the implied warranty of *)
+(* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *)
+(* GNU Lesser General Public License for more details. *)
+(* *)
+(* See the GNU Lesser General Public License version 2.1 *)
+(* for more details (enclosed in the file licenses/LGPLv2.1). *)
+(* *)
+(**************************************************************************)
+
+(* -------------------------------------------------------------------------- *)
+(* --- WP Calculus Driver from Interpreted Automata --- *)
+(* -------------------------------------------------------------------------- *)
+
+module Make(M : Mcfg.S) :
+sig
+
+ val compute : Cil_types.kernel_function -> M.t_env * M.t_prop
+
+end
+
+(* -------------------------------------------------------------------------- *)