path: root/compiler/InterpreterStatements.ml

module T = Types
module PV = PrimitiveValues
module V = Values
module E = Expressions
module C = Contexts
module Subst = Substitute
module A = LlbcAst
module L = Logging
open TypesUtils
open ValuesUtils
module Inv = Invariants
module S = SynthesizeSymbolic
open Utils
open Cps
open InterpreterUtils
open InterpreterProjectors
open InterpreterExpansion
open InterpreterPaths
open InterpreterExpressions

(** The local logger *)
let log = L.statements_log

(** Drop a value at a given place - TODO: factorize this with [assign_to_place] *)
let drop_value (config : C.config) (p : E.place) : cm_fun =
 fun cf ctx ->
  log#ldebug
    (lazy
      ("drop_value: place: " ^ place_to_string ctx p ^ "\n- Initial context:\n"
     ^ eval_ctx_to_string ctx));
  (* Note that we use [Write], not [Move]: we allow to drop values *below* borrows *)
  let access = Write in
  (* First make sure we can access the place, by ending loans or expanding
   * symbolic values along the path, for instance *)
  let cc = update_ctx_along_read_place config access p in
  (* Prepare the place (by ending the outer loans *at* the place). *)
  let cc = comp cc (prepare_lplace config p) in
  (* Replace the value with {!Bottom} *)
  let replace cf (v : V.typed_value) ctx =
    (* Move the value at destination (that we will overwrite) to a dummy variable
     * to preserve the borrows it may contain *)
    let mv = InterpreterPaths.read_place access p ctx in
    let dummy_id = C.fresh_dummy_var_id () in
    let ctx = C.ctx_push_dummy_var ctx dummy_id mv in
    (* Update the destination to ⊥ *)
    let nv = { v with value = V.Bottom } in
    let ctx = write_place access p nv ctx in
    log#ldebug
      (lazy
        ("drop_value: place: " ^ place_to_string ctx p ^ "\n- Final context:\n"
       ^ eval_ctx_to_string ctx));
    cf ctx
  in
  (* Compose and apply *)
  comp cc replace cf ctx

(** Push a dummy variable to the environment *)
let push_dummy_var (vid : C.DummyVarId.id) (v : V.typed_value) : cm_fun =
 fun cf ctx ->
  let ctx = C.ctx_push_dummy_var ctx vid v in
  cf ctx

(** Remove a dummy variable from the environment *)
let remove_dummy_var (vid : C.DummyVarId.id) (cf : V.typed_value -> m_fun) :
    m_fun =
 fun ctx ->
  let ctx, v = C.ctx_remove_dummy_var ctx vid in
  cf v ctx

(** Push an uninitialized variable to the environment *)
let push_uninitialized_var (var : A.var) : cm_fun =
 fun cf ctx ->
  let ctx = C.ctx_push_uninitialized_var ctx var in
  cf ctx

(** Push a list of uninitialized variables to the environment *)
let push_uninitialized_vars (vars : A.var list) : cm_fun =
 fun cf ctx ->
  let ctx = C.ctx_push_uninitialized_vars ctx vars in
  cf ctx

(** Push a variable to the environment *)
let push_var (var : A.var) (v : V.typed_value) : cm_fun =
 fun cf ctx ->
  let ctx = C.ctx_push_var ctx var v in
  cf ctx

(** Push a list of variables to the environment *)
let push_vars (vars : (A.var * V.typed_value) list) : cm_fun =
 fun cf ctx ->
  let ctx = C.ctx_push_vars ctx vars in
  cf ctx

(** Assign a value to a given place.

    Note that this function first pushes the value to assign in a dummy variable,
    then prepares the destination (by ending borrows, etc.) before popping the
    dummy variable and putting in its destination (after having checked that
    preparing the destination didn't introduce ⊥).
 *)
let assign_to_place (config : C.config) (rv : V.typed_value) (p : E.place) :
    cm_fun =
 fun cf ctx ->
  log#ldebug
    (lazy
      ("assign_to_place:" ^ "\n- rv: "
      ^ typed_value_to_string ctx rv
      ^ "\n- p: " ^ place_to_string ctx p ^ "\n- Initial context:\n"
      ^ eval_ctx_to_string ctx));
  (* Push the rvalue to a dummy variable, for bookkeeping *)
  let rvalue_vid = C.fresh_dummy_var_id () in
  let cc = push_dummy_var rvalue_vid rv in
  (* Prepare the destination *)
  let cc = comp cc (prepare_lplace config p) in
  (* Retrieve the rvalue from the dummy variable *)
  let cc = comp cc (fun cf _lv -> remove_dummy_var rvalue_vid cf) in
  (* Update the destination *)
  let move_dest cf (rv : V.typed_value) : m_fun =
   fun ctx ->
    (* Move the value at destination (that we will overwrite) to a dummy variable
     * to preserve the borrows *)
    let mv = InterpreterPaths.read_place Write p ctx in
    let dest_vid = C.fresh_dummy_var_id () in
    let ctx = C.ctx_push_dummy_var ctx dest_vid mv in
    (* Write to the destination *)
    (* Checks - maybe the bookkeeping updated the rvalue and introduced bottoms *)
    assert (not (bottom_in_value ctx.ended_regions rv));
    (* Update the destination *)
    let ctx = write_place Write p rv ctx in
    (* Debug *)
    log#ldebug
      (lazy
        ("assign_to_place:" ^ "\n- rv: "
        ^ typed_value_to_string ctx rv
        ^ "\n- p: " ^ place_to_string ctx p ^ "\n- Final context:\n"
        ^ eval_ctx_to_string ctx));
    (* Continue *)
    cf ctx
  in
  (* Compose and apply *)
  comp cc move_dest cf ctx

(** Evaluate an assertion, when the scrutinee is not symbolic *)
let eval_assertion_concrete (config : C.config) (assertion : A.assertion) :
    st_cm_fun =
 fun cf ctx ->
  (* There won't be any symbolic expansions: fully evaluate the operand *)
  let eval_op = eval_operand config assertion.cond in
  let eval_assert cf (v : V.typed_value) : m_fun =
   fun ctx ->
    match v.value with
    | Primitive (Bool b) ->
        (* Branch *)
        if b = assertion.expected then cf Unit ctx else cf Panic ctx
    | _ ->
        raise
          (Failure ("Expected a boolean, got: " ^ typed_value_to_string ctx v))
  in
  (* Compose and apply *)
  comp eval_op eval_assert cf ctx

(** Evaluates an assertion.
    
    In the case the boolean under scrutinee is symbolic, we synthesize
    a call to [assert ...] then continue in the success branch (and thus
    expand the boolean to [true]).
 *)
let eval_assertion (config : C.config) (assertion : A.assertion) : st_cm_fun =
 fun cf ctx ->
  (* Evaluate the operand *)
  let eval_op = eval_operand config assertion.cond in
  (* Evaluate the assertion *)
  let eval_assert cf (v : V.typed_value) : m_fun =
   fun ctx ->
    assert (v.ty = T.Bool);
    (* We make a choice here: we could completely decouple the concrete and
     * symbolic executions here but choose not to. In the case where we
     * know the concrete value of the boolean we test, we use this value
     * even if we are in symbolic mode. Note that this case should be
     * extremely rare... *)
    match v.value with
    | Primitive (Bool _) ->
        (* Delegate to the concrete evaluation function *)
        eval_assertion_concrete config assertion cf ctx
    | Symbolic sv ->
        assert (config.mode = C.SymbolicMode);
        assert (sv.V.sv_ty = T.Bool);
        (* We continue the execution as if the test had succeeded, and thus
         * perform the symbolic expansion: sv ~~> true.
         * We will of course synthesize an assertion in the generated code
         * (see below). *)
        let ctx =
          apply_symbolic_expansion_non_borrow config sv
            (V.SePrimitive (PV.Bool true)) ctx
        in
        (* Continue *)
        let expr = cf Unit ctx in
        (* Add the synthesized assertion *)
        S.synthesize_assertion v expr
    | _ ->
        raise
          (Failure ("Expected a boolean, got: " ^ typed_value_to_string ctx v))
  in
  (* Compose and apply *)
  comp eval_op eval_assert cf ctx

(** Updates the discriminant of a value at a given place.

    There are two situations:
    - either the discriminant is already the proper one (in which case we
      don't do anything)
    - or it is not the proper one (because the variant is not the proper
      one, or the value is actually {!V.Bottom} - this happens when
      initializing ADT values), in which case we replace the value with
      a variant with all its fields set to {!V.Bottom}.
      For instance, something like: [Cons Bottom Bottom].
 *)
let set_discriminant (config : C.config) (p : E.place)
    (variant_id : T.VariantId.id) : st_cm_fun =
 fun cf ctx ->
  log#ldebug
    (lazy
      ("set_discriminant:" ^ "\n- p: " ^ place_to_string ctx p
     ^ "\n- variant id: "
      ^ T.VariantId.to_string variant_id
      ^ "\n- initial context:\n" ^ eval_ctx_to_string ctx));
  (* Access the value *)
  let access = Write in
  let cc = update_ctx_along_read_place config access p in
  let cc = comp cc (prepare_lplace config p) in
  (* Update the value *)
  let update_value cf (v : V.typed_value) : m_fun =
   fun ctx ->
    match (v.V.ty, v.V.value) with
    | ( T.Adt (((T.AdtId _ | T.Assumed T.Option) as type_id), regions, types),
        V.Adt av ) -> (
        (* There are two situations:
           - either the discriminant is already the proper one (in which case we
             don't do anything)
           - or it is not the proper one, in which case we replace the value with
             a variant with all its fields set to {!Bottom}
        *)
        match av.variant_id with
        | None -> raise (Failure "Found a struct value while expected an enum")
        | Some variant_id' ->
            if variant_id' = variant_id then (* Nothing to do *)
              cf Unit ctx
            else
              (* Replace the value *)
              let bottom_v =
                match type_id with
                | T.AdtId def_id ->
                    compute_expanded_bottom_adt_value
                      ctx.type_context.type_decls def_id (Some variant_id)
                      regions types
                | T.Assumed T.Option ->
                    assert (regions = []);
                    compute_expanded_bottom_option_value variant_id
                      (Collections.List.to_cons_nil types)
                | _ -> raise (Failure "Unreachable")
              in
              assign_to_place config bottom_v p (cf Unit) ctx)
    | ( T.Adt (((T.AdtId _ | T.Assumed T.Option) as type_id), regions, types),
        V.Bottom ) ->
        let bottom_v =
          match type_id with
          | T.AdtId def_id ->
              compute_expanded_bottom_adt_value ctx.type_context.type_decls
                def_id (Some variant_id) regions types
          | T.Assumed T.Option ->
              assert (regions = []);
              compute_expanded_bottom_option_value variant_id
                (Collections.List.to_cons_nil types)
          | _ -> raise (Failure "Unreachable")
        in
        assign_to_place config bottom_v p (cf Unit) ctx
    | _, V.Symbolic _ ->
        assert (config.mode = SymbolicMode);
        (* This is a bit annoying: in theory we should expand the symbolic value
         * then set the discriminant, because in the case the discriminant is
         * exactly the one we set, the fields are left untouched, and in the
         * other cases they are set to Bottom.
         * For now, we forbid setting the discriminant of a symbolic value:
         * setting a discriminant should only be used to initialize a value,
         * or reset an already initialized value, really. *)
        raise (Failure "Unexpected value")
    | _, (V.Adt _ | V.Bottom) -> raise (Failure "Inconsistent state")
    | _, (V.Primitive _ | V.Borrow _ | V.Loan _) ->
        raise (Failure "Unexpected value")
  in
  (* Compose and apply *)
  comp cc update_value cf ctx

(** Push a frame delimiter in the context's environment *)
let ctx_push_frame (ctx : C.eval_ctx) : C.eval_ctx =
  { ctx with env = Frame :: ctx.env }

(** Push a frame delimiter in the context's environment *)
let push_frame : cm_fun = fun cf ctx -> cf (ctx_push_frame ctx)

(** Small helper: compute the type of the return value for a specific
    instantiation of a non-local function.
 *)
let get_non_local_function_return_type (fid : A.assumed_fun_id)
    (region_params : T.erased_region list) (type_params : T.ety list) : T.ety =
  (* [Box::free] has a special treatment *)
  match (fid, region_params, type_params) with
  | A.BoxFree, [], [ _ ] -> mk_unit_ty
  | _ ->
      (* Retrieve the function's signature *)
      let sg = Assumed.get_assumed_sig fid in
      (* Instantiate the return type  *)
      let tsubst =
        Subst.make_type_subst
          (List.map (fun v -> v.T.index) sg.type_params)
          type_params
      in
      Subst.erase_regions_substitute_types tsubst sg.output

let move_return_value (config : C.config) (cf : V.typed_value -> m_fun) : m_fun
    =
 fun ctx ->
  let ret_vid = E.VarId.zero in
  let cc = eval_operand config (E.Move (mk_place_from_var_id ret_vid)) in
  cc cf ctx

let pop_frame (config : C.config) (cf : V.typed_value -> m_fun) : m_fun =
 fun ctx ->
  (* Debug *)
  log#ldebug (lazy ("pop_frame:\n" ^ eval_ctx_to_string ctx));

  (* List the local variables, but the return variable *)
  let ret_vid = E.VarId.zero in
  let rec list_locals env =
    match env with
    | [] -> raise (Failure "Inconsistent environment")
    | C.Abs _ :: env -> list_locals env
    | C.Var (DummyBinder _, _) :: env -> list_locals env
    | C.Var (VarBinder var, _) :: env ->
        let locals = list_locals env in
        if var.index <> ret_vid then var.index :: locals else locals
    | C.Frame :: _ -> []
  in
  let locals : E.VarId.id list = list_locals ctx.env in
  (* Debug *)
  log#ldebug
    (lazy
      ("pop_frame: locals in which to drop the outer loans: ["
      ^ String.concat "," (List.map E.VarId.to_string locals)
      ^ "]"));

  (* Move the return value out of the return variable *)
  let cc = move_return_value config in
  (* Sanity check *)
  let cc =
    comp_check_value cc (fun ret_value ctx ->
        assert (not (bottom_in_value ctx.ended_regions ret_value)))
  in

  (* Drop the outer *loans* we find in the local variables *)
  let cf_drop_loans_in_locals cf (ret_value : V.typed_value) : m_fun =
    (* Drop the loans *)
    let locals = List.rev locals in
    let cf_drop =
      List.fold_left
        (fun cf lid ->
          drop_outer_loans_at_lplace config (mk_place_from_var_id lid) cf)
        (cf ret_value) locals
    in
    (* Apply *)
    cf_drop
  in
  let cc = comp cc cf_drop_loans_in_locals in
  (* Debug *)
  let cc =
    comp_check_value cc (fun _ ctx ->
        log#ldebug
          (lazy
            ("pop_frame: after dropping outer loans in local variables:\n"
           ^ eval_ctx_to_string ctx)))
  in

  (* Pop the frame - we remove the [Frame] delimiter, and reintroduce all
   * the local variables (which may still contain borrow permissions - but
   * no outer loans) as dummy variables in the caller frame *)
  let rec pop env =
    match env with
    | [] -> raise (Failure "Inconsistent environment")
    | C.Abs abs :: env -> C.Abs abs :: pop env
    | C.Var (_, v) :: env ->
        let vid = C.fresh_dummy_var_id () in
        C.Var (C.DummyBinder vid, v) :: pop env
    | C.Frame :: env -> (* Stop here *) env
  in
  let cf_pop cf (ret_value : V.typed_value) : m_fun =
   fun ctx ->
    let env = pop ctx.env in
    let ctx = { ctx with env } in
    cf ret_value ctx
  in
  (* Compose and apply *)
  comp cc cf_pop cf ctx

(** Pop the current frame and assign the returned value to its destination. *)
let pop_frame_assign (config : C.config) (dest : E.place) : cm_fun =
  let cf_pop = pop_frame config in
  let cf_assign cf ret_value : m_fun =
    assign_to_place config ret_value dest cf
  in
  comp cf_pop cf_assign

(** Auxiliary function - see {!eval_non_local_function_call} *)
let eval_replace_concrete (_config : C.config)
    (_region_params : T.erased_region list) (_type_params : T.ety list) : cm_fun
    =
 fun _cf _ctx -> raise Unimplemented

(** Auxiliary function - see {!eval_non_local_function_call} *)
let eval_box_new_concrete (config : C.config)
    (region_params : T.erased_region list) (type_params : T.ety list) : cm_fun =
 fun cf ctx ->
  (* Check and retrieve the arguments *)
  match (region_params, type_params, ctx.env) with
  | ( [],
      [ boxed_ty ],
      Var (VarBinder input_var, input_value)
      :: Var (_ret_var, _)
      :: C.Frame :: _ ) ->
      (* Required type checking *)
      assert (input_value.V.ty = boxed_ty);

      (* Move the input value *)
      let cf_move =
        eval_operand config (E.Move (mk_place_from_var_id input_var.C.index))
      in

      (* Create the new box *)
      let cf_create cf (moved_input_value : V.typed_value) : m_fun =
        (* Create the box value *)
        let box_ty = T.Adt (T.Assumed T.Box, [], [ boxed_ty ]) in
        let box_v =
          V.Adt { variant_id = None; field_values = [ moved_input_value ] }
        in
        let box_v = mk_typed_value box_ty box_v in

        (* Move this value to the return variable *)
        let dest = mk_place_from_var_id E.VarId.zero in
        let cf_assign = assign_to_place config box_v dest in

        (* Continue *)
        cf_assign cf
      in

      (* Compose and apply *)
      comp cf_move cf_create cf ctx
  | _ -> raise (Failure "Inconsistent state")

(** Auxiliary function which factorizes code to evaluate [std::Deref::deref]
    and [std::DerefMut::deref_mut] - see {!eval_non_local_function_call} *)
let eval_box_deref_mut_or_shared_concrete (config : C.config)
    (region_params : T.erased_region list) (type_params : T.ety list)
    (is_mut : bool) : cm_fun =
 fun cf ctx ->
  (* Check the arguments *)
  match (region_params, type_params, ctx.env) with
  | ( [],
      [ boxed_ty ],
      Var (VarBinder input_var, input_value)
      :: Var (_ret_var, _)
      :: C.Frame :: _ ) ->
      (* Required type checking. We must have:
         - input_value.ty = & (mut) Box<ty>
         - boxed_ty = ty
         for some ty
      *)
      (let _, input_ty, ref_kind = ty_get_ref input_value.V.ty in
       assert (match ref_kind with T.Shared -> not is_mut | T.Mut -> is_mut);
       let input_ty = ty_get_box input_ty in
       assert (input_ty = boxed_ty));

      (* Borrow the boxed value *)
      let p =
        { E.var_id = input_var.C.index; projection = [ E.Deref; E.DerefBox ] }
      in
      let borrow_kind = if is_mut then E.Mut else E.Shared in
      let rv = E.Ref (p, borrow_kind) in
      let cf_borrow = eval_rvalue_not_global config rv in

      (* Move the borrow to its destination *)
      let cf_move cf res : m_fun =
        match res with
        | Error EPanic ->
            (* We can't get there by borrowing a value *)
            raise (Failure "Unreachable")
        | Ok borrowed_value ->
            (* Move and continue *)
            let destp = mk_place_from_var_id E.VarId.zero in
            assign_to_place config borrowed_value destp cf
      in

      (* Compose and apply *)
      comp cf_borrow cf_move cf ctx
  | _ -> raise (Failure "Inconsistent state")

(** Auxiliary function - see {!eval_non_local_function_call} *)
let eval_box_deref_concrete (config : C.config)
    (region_params : T.erased_region list) (type_params : T.ety list) : cm_fun =
  let is_mut = false in
  eval_box_deref_mut_or_shared_concrete config region_params type_params is_mut

(** Auxiliary function - see {!eval_non_local_function_call} *)
let eval_box_deref_mut_concrete (config : C.config)
    (region_params : T.erased_region list) (type_params : T.ety list) : cm_fun =
  let is_mut = true in
  eval_box_deref_mut_or_shared_concrete config region_params type_params is_mut

(** Auxiliary function - see {!eval_non_local_function_call}.

    [Box::free] is not handled the same way as the other assumed functions:
    - in the regular case, whenever we need to evaluate an assumed function,
      we evaluate the operands, push a frame, call a dedicated function
      to correctly update the variables in the frame (and mimic the execution
      of a body) and finally pop the frame
    - in the case of [Box::free]: the value given to this function is often
      of the form [Box(⊥)] because we can move the value out of the
      box before freeing the box. It makes it invalid to see box_free as a
      "regular" function: it is not valid to call a function with arguments
      which contain [⊥]. For this reason, we execute [Box::free] as drop_value,
      but this is a bit annoying with regards to the semantics...

    Followingly this function doesn't behave like the others: it does not expect
    a stack frame to have been pushed, but rather simply behaves like {!drop_value}.
    It thus updates the box value (by calling {!drop_value}) and updates
    the destination (by setting it to [()]).
*)
let eval_box_free (config : C.config) (region_params : T.erased_region list)
    (type_params : T.ety list) (args : E.operand list) (dest : E.place) : cm_fun
    =
 fun cf ctx ->
  match (region_params, type_params, args) with
  | [], [ boxed_ty ], [ E.Move input_box_place ] ->
      (* Required type checking *)
      let input_box = InterpreterPaths.read_place Write input_box_place ctx in
      (let input_ty = ty_get_box input_box.V.ty in
       assert (input_ty = boxed_ty));

      (* Drop the value *)
      let cc = drop_value config input_box_place in

      (* Update the destination by setting it to [()] *)
      let cc = comp cc (assign_to_place config mk_unit_value dest) in

      (* Continue *)
      cc cf ctx
  | _ -> raise (Failure "Inconsistent state")

(** Auxiliary function - see {!eval_non_local_function_call} *)
let eval_vec_function_concrete (_config : C.config) (_fid : A.assumed_fun_id)
    (_region_params : T.erased_region list) (_type_params : T.ety list) : cm_fun
    =
 fun _cf _ctx -> raise Unimplemented

(** Evaluate a non-local function call in concrete mode *)
let eval_non_local_function_call_concrete (config : C.config)
    (fid : A.assumed_fun_id) (region_params : T.erased_region list)
    (type_params : T.ety list) (args : E.operand list) (dest : E.place) : cm_fun
    =
  (* There are two cases (and this is extremely annoying):
     - the function is not box_free
     - the function is box_free
     See {!eval_box_free}
  *)
  match fid with
  | A.BoxFree ->
      (* Degenerate case: box_free *)
      eval_box_free config region_params type_params args dest
  | _ ->
      (* "Normal" case: not box_free *)
      (* Evaluate the operands *)
      (*      let ctx, args_vl = eval_operands config ctx args in *)
      let cf_eval_ops = eval_operands config args in

      (* Evaluate the call
       *
       * Style note: at some point we used {!comp_transmit} to
       * transmit the result of {!eval_operands} above down to {!push_vars}
       * below, without having to introduce an intermediary function call,
       * but it made it less clear where the computed values came from,
       * so we reversed the modifications. *)
      let cf_eval_call cf (args_vl : V.typed_value list) : m_fun =
        (* Push the stack frame: we initialize the frame with the return variable,
           and one variable per input argument *)
        let cc = push_frame in

        (* Create and push the return variable *)
        let ret_vid = E.VarId.zero in
        let ret_ty =
          get_non_local_function_return_type fid region_params type_params
        in
        let ret_var = mk_var ret_vid (Some "@return") ret_ty in
        let cc = comp cc (push_uninitialized_var ret_var) in

        (* Create and push the input variables *)
        let input_vars =
          E.VarId.mapi_from1
            (fun id (v : V.typed_value) -> (mk_var id None v.V.ty, v))
            args_vl
        in
        let cc = comp cc (push_vars input_vars) in

        (* "Execute" the function body. As the functions are assumed, here we call
         * custom functions to perform the proper manipulations: we don't have
         * access to a body. *)
        let cf_eval_body : cm_fun =
          match fid with
          | A.Replace -> eval_replace_concrete config region_params type_params
          | BoxNew -> eval_box_new_concrete config region_params type_params
          | BoxDeref -> eval_box_deref_concrete config region_params type_params
          | BoxDerefMut ->
              eval_box_deref_mut_concrete config region_params type_params
          | BoxFree ->
              (* Should have been treated above *) raise (Failure "Unreachable")
          | VecNew | VecPush | VecInsert | VecLen | VecIndex | VecIndexMut ->
              eval_vec_function_concrete config fid region_params type_params
        in

        let cc = comp cc cf_eval_body in

        (* Pop the frame *)
        let cc = comp cc (pop_frame_assign config dest) in

        (* Continue *)
        cc cf
      in
      (* Compose and apply *)
      comp cf_eval_ops cf_eval_call

let instantiate_fun_sig (type_params : T.ety list) (sg : A.fun_sig) :
    A.inst_fun_sig =
  (* Generate fresh abstraction ids and create a substitution from region
   * group ids to abstraction ids *)
  let rg_abs_ids_bindings =
    List.map
      (fun rg ->
        let abs_id = C.fresh_abstraction_id () in
        (rg.T.id, abs_id))
      sg.regions_hierarchy
  in
  let asubst_map : V.AbstractionId.id T.RegionGroupId.Map.t =
    List.fold_left
      (fun mp (rg_id, abs_id) -> T.RegionGroupId.Map.add rg_id abs_id mp)
      T.RegionGroupId.Map.empty rg_abs_ids_bindings
  in
  let asubst (rg_id : T.RegionGroupId.id) : V.AbstractionId.id =
    T.RegionGroupId.Map.find rg_id asubst_map
  in
  (* Generate fresh regions and their substitutions *)
  let _, rsubst, _ = Subst.fresh_regions_with_substs sg.region_params in
  (* Generate the type substitution
   * Note that we need the substitution to map the type variables to
   * {!rty} types (not {!ety}). In order to do that, we convert the
   * type parameters to types with regions. This is possible only
   * if those types don't contain any regions.
   * This is a current limitation of the analysis: there is still some
   * work to do to properly handle full type parametrization.
   * *)
  let rtype_params = List.map ety_no_regions_to_rty type_params in
  let tsubst =
    Subst.make_type_subst
      (List.map (fun v -> v.T.index) sg.type_params)
      rtype_params
  in
  (* Substitute the signature *)
  let inst_sig = Subst.substitute_signature asubst rsubst tsubst sg in
  (* Return *)
  inst_sig

(** Helper
 
    Create abstractions (with no avalues, which have to be inserted afterwards)
    from a list of abs region groups.
    
    [region_can_end]: gives the region groups from which we generate functions
    which can end or not.
 *)
let create_empty_abstractions_from_abs_region_groups
    (kind : T.RegionGroupId.id -> V.abs_kind) (rgl : A.abs_region_group list)
    (region_can_end : T.RegionGroupId.id -> bool) : V.abs list =
  (* We use a reference to progressively create a map from abstraction ids
   * to set of ancestor regions. Note that {!abs_to_ancestors_regions} [abs_id]
   * returns the union of:
   * - the regions of the ancestors of abs_id
   * - the regions of abs_id
   *)
  let abs_to_ancestors_regions : T.RegionId.Set.t V.AbstractionId.Map.t ref =
    ref V.AbstractionId.Map.empty
  in
  (* Auxiliary function to create one abstraction *)
  let create_abs (rg_id : T.RegionGroupId.id) (rg : A.abs_region_group) : V.abs
      =
    let abs_id = rg.T.id in
    let original_parents = rg.parents in
    let parents =
      List.fold_left
        (fun s pid -> V.AbstractionId.Set.add pid s)
        V.AbstractionId.Set.empty rg.parents
    in
    let regions =
      List.fold_left
        (fun s rid -> T.RegionId.Set.add rid s)
        T.RegionId.Set.empty rg.regions
    in
    let ancestors_regions =
      List.fold_left
        (fun acc parent_id ->
          T.RegionId.Set.union acc
            (V.AbstractionId.Map.find parent_id !abs_to_ancestors_regions))
        T.RegionId.Set.empty rg.parents
    in
    let ancestors_regions_union_current_regions =
      T.RegionId.Set.union ancestors_regions regions
    in
    let can_end = region_can_end rg_id in
    abs_to_ancestors_regions :=
      V.AbstractionId.Map.add abs_id ancestors_regions_union_current_regions
        !abs_to_ancestors_regions;
    (* Create the abstraction *)
    {
      V.abs_id;
      kind = kind rg_id;
      can_end;
      parents;
      original_parents;
      regions;
      ancestors_regions;
      avalues = [];
    }
  in
  (* Apply *)
  T.RegionGroupId.mapi create_abs rgl

let create_push_abstractions_from_abs_region_groups
    (kind : T.RegionGroupId.id -> V.abs_kind) (rgl : A.abs_region_group list)
    (region_can_end : T.RegionGroupId.id -> bool)
    (compute_abs_avalues :
      V.abs -> C.eval_ctx -> C.eval_ctx * V.typed_avalue list)
    (ctx : C.eval_ctx) : C.eval_ctx =
  (* Initialize the abstractions as empty (i.e., with no avalues) abstractions *)
  let empty_absl =
    create_empty_abstractions_from_abs_region_groups kind rgl region_can_end
  in

  (* Compute and add the avalues to the abstractions, the insert the abstractions
   * in the context. *)
  let insert_abs (ctx : C.eval_ctx) (abs : V.abs) : C.eval_ctx =
    (* Compute the values to insert in the abstraction *)
    let ctx, avalues = compute_abs_avalues abs ctx in
    (* Add the avalues to the abstraction *)
    let abs = { abs with avalues } in
    (* Insert the abstraction in the context *)
    let ctx = { ctx with env = Abs abs :: ctx.env } in
    (* Return *)
    ctx
  in
  List.fold_left insert_abs ctx empty_absl

(** Evaluate a statement *)
let rec eval_statement (config : C.config) (st : A.statement) : st_cm_fun =
 fun cf ctx ->
  (* Debugging *)
  log#ldebug
    (lazy
      ("\n**About to evaluate statement**: [\n"
      ^ statement_to_string_with_tab ctx st
      ^ "\n]\n\n**Context**:\n" ^ eval_ctx_to_string ctx ^ "\n\n"));

  (* Expand the symbolic values if necessary - we need to do that before
   * checking the invariants *)
  let cc = greedy_expand_symbolic_values config in
  (* Sanity check *)
  let cc = comp cc Inv.cf_check_invariants in

  (* Evaluate *)
  let cf_eval_st cf : m_fun =
   fun ctx ->
    match st.content with
    | A.Assign (p, rvalue) -> (
        (* We handle global assignments separately *)
        match rvalue with
        | E.Global gid ->
            (* Evaluate the global *)
            eval_global config p gid cf ctx
        | _ ->
            (* Evaluate the rvalue *)
            let cf_eval_rvalue = eval_rvalue_not_global config rvalue in
            (* Assign *)
            let cf_assign cf (res : (V.typed_value, eval_error) result) ctx =
              log#ldebug
                (lazy
                  ("about to assign to place: " ^ place_to_string ctx p
                 ^ "\n- Context:\n" ^ eval_ctx_to_string ctx));
              match res with
              | Error EPanic -> cf Panic ctx
              | Ok rv -> (
                  let expr = assign_to_place config rv p (cf Unit) ctx in
                  (* Update the synthesized AST - here we store meta-information.
                   * We do it only in specific cases (it is not always useful, and
                   * also it can lead to issues - for instance, if we borrow an
                   * reserved borrow, we later can't translate it to pure values...) *)
                  match rvalue with
                  | E.Global _ -> raise (Failure "Unreachable")
                  | E.Use _
                  | E.Ref (_, (E.Shared | E.Mut | E.TwoPhaseMut))
                  | E.UnaryOp _ | E.BinaryOp _ | E.Discriminant _
                  | E.Aggregate _ ->
                      let rp = rvalue_get_place rvalue in
                      let rp =
                        match rp with
                        | Some rp -> Some (S.mk_mplace rp ctx)
                        | None -> None
                      in
                      S.synthesize_assignment (S.mk_mplace p ctx) rv rp expr)
            in

            (* Compose and apply *)
            comp cf_eval_rvalue cf_assign cf ctx)
    | A.FakeRead p -> eval_fake_read config p (cf Unit) ctx
    | A.SetDiscriminant (p, variant_id) ->
        set_discriminant config p variant_id cf ctx
    | A.Drop p -> drop_value config p (cf Unit) ctx
    | A.Assert assertion -> eval_assertion config assertion cf ctx
    | A.Call call -> eval_function_call config call cf ctx
    | A.Panic -> cf Panic ctx
    | A.Return -> cf Return ctx
    | A.Break i -> cf (Break i) ctx
    | A.Continue i -> cf (Continue i) ctx
    | A.Nop -> cf Unit ctx
    | A.Sequence (st1, st2) ->
        (* Evaluate the first statement *)
        let cf_st1 = eval_statement config st1 in
        (* Evaluate the sequence *)
        let cf_st2 cf res =
          match res with
          (* Evaluation successful: evaluate the second statement *)
          | Unit -> eval_statement config st2 cf
          (* Control-flow break: transmit. We enumerate the cases on purpose *)
          | Panic | Break _ | Continue _ | Return | EndEnterLoop | EndContinue
            ->
              cf res
        in
        (* Compose and apply *)
        comp cf_st1 cf_st2 cf ctx
    | A.Loop loop_body ->
        InterpreterLoops.eval_loop config
          (eval_statement config loop_body)
          cf ctx
    | A.Switch switch -> eval_switch config switch cf ctx
  in
  (* Compose and apply *)
  comp cc cf_eval_st cf ctx

and eval_global (config : C.config) (dest : E.place) (gid : LA.GlobalDeclId.id)
    : st_cm_fun =
 fun cf ctx ->
  let global = C.ctx_lookup_global_decl ctx gid in
  match config.mode with
  | ConcreteMode ->
      (* Treat the evaluation of the global as a call to the global body (without arguments) *)
      (eval_local_function_call_concrete config global.body_id [] [] [] dest)
        cf ctx
  | SymbolicMode ->
      (* Generate a fresh symbolic value. In the translation, this fresh symbolic value will be
       * defined as equal to the value of the global (see {!S.synthesize_global_eval}). *)
      let sval =
        mk_fresh_symbolic_value V.Global (ety_no_regions_to_rty global.ty)
      in
      let cc =
        assign_to_place config (mk_typed_value_from_symbolic_value sval) dest
      in
      let e = cc (cf Unit) ctx in
      S.synthesize_global_eval gid sval e

(** Evaluate a switch *)
and eval_switch (config : C.config) (switch : A.switch) : st_cm_fun =
 fun cf ctx ->
  (* We evaluate the operand in two steps:
   * first we prepare it, then we check if its value is concrete or
   * symbolic. If it is concrete, we can then evaluate the operand
   * directly, otherwise we must first expand the value.
   * Note that we can't fully evaluate the operand *then* expand the
   * value if it is symbolic, because the value may have been move
   * (and would thus floating in thin air...)!
   * *)
  (* Match on the targets *)
  let cf_match : st_cm_fun =
   fun cf ctx ->
    match switch with
    | A.If (op, st1, st2) ->
        (* Evaluate the operand *)
        let cf_eval_op = eval_operand config op in
        (* Switch on the value *)
        let cf_if (cf : st_m_fun) (op_v : V.typed_value) : m_fun =
         fun ctx ->
          match op_v.value with
          | V.Primitive (PV.Bool b) ->
              (* Evaluate the if and the branch body *)
              let cf_branch cf : m_fun =
                (* Branch *)
                if b then eval_statement config st1 cf
                else eval_statement config st2 cf
              in
              (* Compose the continuations *)
              cf_branch cf ctx
          | V.Symbolic sv ->
              (* Expand the symbolic boolean, and continue by evaluating
               * the branches *)
              let cf_true : st_cm_fun = eval_statement config st1 in
              let cf_false : st_cm_fun = eval_statement config st2 in
              expand_symbolic_bool config sv
                (S.mk_opt_place_from_op op ctx)
                cf_true cf_false cf ctx
          | _ -> raise (Failure "Inconsistent state")
        in
        (* Compose *)
        comp cf_eval_op cf_if cf ctx
    | A.SwitchInt (op, int_ty, stgts, otherwise) ->
        (* Evaluate the operand *)
        let cf_eval_op = eval_operand config op in
        (* Switch on the value *)
        let cf_switch (cf : st_m_fun) (op_v : V.typed_value) : m_fun =
         fun ctx ->
          match op_v.value with
          | V.Primitive (PV.Scalar sv) ->
              (* Evaluate the branch *)
              let cf_eval_branch cf =
                (* Sanity check *)
                assert (sv.PV.int_ty = int_ty);
                (* Find the branch *)
                match List.find_opt (fun (svl, _) -> List.mem sv svl) stgts with
                | None -> eval_statement config otherwise cf
                | Some (_, tgt) -> eval_statement config tgt cf
              in
              (* Compose *)
              cf_eval_branch cf ctx
          | V.Symbolic sv ->
              (* Expand the symbolic value and continue by evaluating the
               * proper branches *)
              let stgts =
                List.map
                  (fun (cv, tgt_st) -> (cv, eval_statement config tgt_st))
                  stgts
              in
              (* Several branches may be grouped together: every branch is described
               * by a pair (list of values, branch expression).
               * In order to do a symbolic evaluation, we make this "flat" by
               * de-grouping the branches. *)
              let stgts =
                List.concat
                  (List.map
                     (fun (vl, st) -> List.map (fun v -> (v, st)) vl)
                     stgts)
              in
              (* Translate the otherwise branch *)
              let otherwise = eval_statement config otherwise in
              (* Expand and continue *)
              expand_symbolic_int config sv
                (S.mk_opt_place_from_op op ctx)
                int_ty stgts otherwise cf ctx
          | _ -> raise (Failure "Inconsistent state")
        in
        (* Compose *)
        comp cf_eval_op cf_switch cf ctx
    | A.Match (p, stgts, otherwise) ->
        (* Access the place *)
        let access = Read in
        let expand_prim_copy = false in
        let cf_read_p cf : m_fun =
          access_rplace_reorganize_and_read config expand_prim_copy access p cf
        in
        (* Match on the value *)
        let cf_match (cf : st_m_fun) (p_v : V.typed_value) : m_fun =
         fun ctx ->
          (* The value may be shared: we need to ignore the shared loans
             to read the value itself *)
          let p_v = value_strip_shared_loans p_v in
          (* Match *)
          match p_v.value with
          | V.Adt adt -> (
              (* Evaluate the discriminant *)
              let dv = Option.get adt.variant_id in
              (* Find the branch, evaluate and continue *)
              match List.find_opt (fun (svl, _) -> List.mem dv svl) stgts with
              | None -> eval_statement config otherwise cf ctx
              | Some (_, tgt) -> eval_statement config tgt cf ctx)
          | V.Symbolic sv ->
              (* Expand the symbolic value - may lead to branching *)
              let cf_expand =
                expand_symbolic_adt config sv (Some (S.mk_mplace p ctx))
              in
              (* Re-evaluate the switch - the value is not symbolic anymore,
                 which means we will go to the other branch *)
              cf_expand (eval_switch config switch) cf ctx
          | _ -> raise (Failure "Inconsistent state")
        in
        (* Compose *)
        comp cf_read_p cf_match cf ctx
  in
  (* Compose the continuations *)
  cf_match cf ctx

(** Evaluate a function call (auxiliary helper for [eval_statement]) *)
and eval_function_call (config : C.config) (call : A.call) : st_cm_fun =
  (* There are two cases:
     - this is a local function, in which case we execute its body
     - this is a non-local function, in which case there is a special treatment
  *)
  match call.func with
  | A.Regular fid ->
      eval_local_function_call config fid call.region_args call.type_args
        call.args call.dest
  | A.Assumed fid ->
      eval_non_local_function_call config fid call.region_args call.type_args
        call.args call.dest

(** Evaluate a local (i.e., non-assumed) function call in concrete mode *)
and eval_local_function_call_concrete (config : C.config) (fid : A.FunDeclId.id)
    (region_args : T.erased_region list) (type_args : T.ety list)
    (args : E.operand list) (dest : E.place) : st_cm_fun =
 fun cf ctx ->
  assert (region_args = []);

  (* Retrieve the (correctly instantiated) body *)
  let def = C.ctx_lookup_fun_decl ctx fid in
  (* We can evaluate the function call only if it is not opaque *)
  let body =
    match def.body with
    | None ->
        raise
          (Failure
             ("Can't evaluate a call to an opaque function: "
             ^ Print.name_to_string def.name))
    | Some body -> body
  in
  let tsubst =
    Subst.make_type_subst
      (List.map (fun v -> v.T.index) def.A.signature.type_params)
      type_args
  in
  let locals, body_st = Subst.fun_body_substitute_in_body tsubst body in

  (* Evaluate the input operands *)
  assert (List.length args = body.A.arg_count);
  let cc = eval_operands config args in

  (* Push a frame delimiter - we use {!comp_transmit} to transmit the result
   * of the operands evaluation from above to the functions afterwards, while
   * ignoring it in this function *)
  let cc = comp_transmit cc push_frame in

  (* Compute the initial values for the local variables *)
  (* 1. Push the return value *)
  let ret_var, locals =
    match locals with
    | ret_ty :: locals -> (ret_ty, locals)
    | _ -> raise (Failure "Unreachable")
  in
  let input_locals, locals =
    Collections.List.split_at locals body.A.arg_count
  in

  let cc = comp_transmit cc (push_var ret_var (mk_bottom ret_var.var_ty)) in

  (* 2. Push the input values *)
  let cf_push_inputs cf args =
    let inputs = List.combine input_locals args in
    (* Note that this function checks that the variables and their values
     * have the same type (this is important) *)
    push_vars inputs cf
  in
  let cc = comp cc cf_push_inputs in

  (* 3. Push the remaining local variables (initialized as {!Bottom}) *)
  let cc = comp cc (push_uninitialized_vars locals) in

  (* Execute the function body *)
  let cc = comp cc (eval_function_body config body_st) in

  (* Pop the stack frame and move the return value to its destination *)
  let cf_finish cf res =
    match res with
    | Panic -> cf Panic
    | Return ->
        (* Pop the stack frame, retrieve the return value, move it to
         * its destination and continue *)
        pop_frame_assign config dest (cf Unit)
    | Break _ | Continue _ | Unit | EndEnterLoop | EndContinue ->
        raise (Failure "Unreachable")
  in
  let cc = comp cc cf_finish in

  (* Continue *)
  cc cf ctx

(** Evaluate a local (i.e., non-assumed) function call in symbolic mode *)
and eval_local_function_call_symbolic (config : C.config) (fid : A.FunDeclId.id)
    (region_args : T.erased_region list) (type_args : T.ety list)
    (args : E.operand list) (dest : E.place) : st_cm_fun =
 fun cf ctx ->
  (* Retrieve the (correctly instantiated) signature *)
  let def = C.ctx_lookup_fun_decl ctx fid in
  let sg = def.A.signature in
  (* Instantiate the signature and introduce fresh abstraction and region ids
   * while doing so *)
  let inst_sg = instantiate_fun_sig type_args sg in
  (* Sanity check *)
  assert (List.length args = List.length def.A.signature.inputs);
  (* Evaluate the function call *)
  eval_function_call_symbolic_from_inst_sig config (A.Regular fid) inst_sg
    region_args type_args args dest cf ctx

(** Evaluate a function call in symbolic mode by using the function signature.

    This allows us to factorize the evaluation of local and non-local function
    calls in symbolic mode: only their signatures matter.
 *)
and eval_function_call_symbolic_from_inst_sig (config : C.config)
    (fid : A.fun_id) (inst_sg : A.inst_fun_sig)
    (region_args : T.erased_region list) (type_args : T.ety list)
    (args : E.operand list) (dest : E.place) : st_cm_fun =
 fun cf ctx ->
  assert (region_args = []);
  (* Generate a fresh symbolic value for the return value *)
  let ret_sv_ty = inst_sg.A.output in
  let ret_spc = mk_fresh_symbolic_value V.FunCallRet ret_sv_ty in
  let ret_value = mk_typed_value_from_symbolic_value ret_spc in
  let ret_av regions =
    mk_aproj_loans_value_from_symbolic_value regions ret_spc
  in
  let args_places = List.map (fun p -> S.mk_opt_place_from_op p ctx) args in
  let dest_place = Some (S.mk_mplace dest ctx) in

  (* Evaluate the input operands *)
  let cc = eval_operands config args in

  (* Generate the abstractions and insert them in the context *)
  let abs_ids = List.map (fun rg -> rg.T.id) inst_sg.regions_hierarchy in
  let cf_call cf (args : V.typed_value list) : m_fun =
   fun ctx ->
    let args_with_rtypes = List.combine args inst_sg.A.inputs in

    (* Check the type of the input arguments *)
    assert (
      List.for_all
        (fun ((arg, rty) : V.typed_value * T.rty) ->
          arg.V.ty = Subst.erase_regions rty)
        args_with_rtypes);
    (* Check that the input arguments don't contain symbolic values that can't 
     * be fed to functions (i.e., symbolic values output from function return
     * values and which contain borrows of borrows can't be used as function
     * inputs *)
    assert (
      List.for_all
        (fun arg ->
          not (value_has_ret_symbolic_value_with_borrow_under_mut ctx arg))
        args);

    (* Initialize the abstractions and push them in the context.
     * First, we define the function which, given an initialized, empty
     * abstraction, computes the avalues which should be inserted inside.
     *)
    let compute_abs_avalues (abs : V.abs) (ctx : C.eval_ctx) :
        C.eval_ctx * V.typed_avalue list =
      (* Project over the input values *)
      let ctx, args_projs =
        List.fold_left_map
          (fun ctx (arg, arg_rty) ->
            apply_proj_borrows_on_input_value config ctx abs.regions
              abs.ancestors_regions arg arg_rty)
          ctx args_with_rtypes
      in
      (* Group the input and output values *)
      (ctx, List.append args_projs [ ret_av abs.regions ])
    in
    (* Actually initialize and insert the abstractions *)
    let call_id = C.fresh_fun_call_id () in
    let region_can_end _ = true in
    let ctx =
      create_push_abstractions_from_abs_region_groups
        (fun rg_id -> V.FunCall (call_id, rg_id))
        inst_sg.A.regions_hierarchy region_can_end compute_abs_avalues ctx
    in

    (* Apply the continuation *)
    let expr = cf ctx in

    (* Synthesize the symbolic AST *)
    S.synthesize_regular_function_call fid call_id abs_ids type_args args
      args_places ret_spc dest_place expr
  in
  let cc = comp cc cf_call in

  (* Move the return value to its destination *)
  let cc = comp cc (assign_to_place config ret_value dest) in

  (* End the abstractions which don't contain loans and don't have parent
   * abstractions.
   * We do the general, nested borrows case here: we end abstractions, then
   * retry (because then we might end their children abstractions)
   *)
  let abs_ids = ref abs_ids in
  let rec end_abs_with_no_loans cf : m_fun =
   fun ctx ->
    (* Find the abstractions which don't contain loans *)
    let no_loans_abs, with_loans_abs =
      List.partition
        (fun abs_id ->
          (* Lookup the abstraction *)
          let abs = C.ctx_lookup_abs ctx abs_id in
          (* Check if it has parents *)
          V.AbstractionId.Set.is_empty abs.parents
          (* Check if it contains non-ignored loans *)
          && Option.is_none
               (InterpreterBorrowsCore
                .get_first_non_ignored_aloan_in_abstraction abs))
        !abs_ids
    in
    (* Check if there are abstractions to end *)
    if no_loans_abs <> [] then (
      (* Update the reference to the list of asbtraction ids, for the recursive calls *)
      abs_ids := with_loans_abs;
      (* End the abstractions which can be ended *)
      let no_loans_abs = V.AbstractionId.Set.of_list no_loans_abs in
      let cc = InterpreterBorrows.end_abstractions config no_loans_abs in
      (* Recursive call *)
      let cc = comp cc end_abs_with_no_loans in
      (* Continue *)
      cc cf ctx)
    else (* No abstractions to end: continue *)
      cf ctx
  in
  (* Try to end the abstractions with no loans if:
   * - the option is enabled
   * - the function returns unit
   * (see the documentation of {!config} for more information)
   *)
  let cc =
    if Config.return_unit_end_abs_with_no_loans && ty_is_unit inst_sg.output
    then comp cc end_abs_with_no_loans
    else cc
  in

  (* Continue - note that we do as if the function call has been successful,
   * by giving {!Unit} to the continuation, because we place us in the case
   * where we haven't panicked. Of course, the translation needs to take the
   * panic case into account... *)
  cc (cf Unit) ctx

(** Evaluate a non-local function call in symbolic mode *)
and eval_non_local_function_call_symbolic (config : C.config)
    (fid : A.assumed_fun_id) (region_args : T.erased_region list)
    (type_args : T.ety list) (args : E.operand list) (dest : E.place) :
    st_cm_fun =
 fun cf ctx ->
  (* Sanity check: make sure the type parameters don't contain regions -
   * this is a current limitation of our synthesis *)
  assert (
    List.for_all
      (fun ty -> not (ty_has_borrows ctx.type_context.type_infos ty))
      type_args);

  (* There are two cases (and this is extremely annoying):
     - the function is not box_free
     - the function is box_free
       See {!eval_box_free}
  *)
  match fid with
  | A.BoxFree ->
      (* Degenerate case: box_free - note that this is not really a function
       * call: no need to call a "synthesize_..." function *)
      eval_box_free config region_args type_args args dest (cf Unit) ctx
  | _ ->
      (* "Normal" case: not box_free *)
      (* In symbolic mode, the behaviour of a function call is completely defined
       * by the signature of the function: we thus simply generate correctly
       * instantiated signatures, and delegate the work to an auxiliary function *)
      let inst_sig =
        match fid with
        | A.BoxFree ->
            (* should have been treated above *)
            raise (Failure "Unreachable")
        | _ -> instantiate_fun_sig type_args (Assumed.get_assumed_sig fid)
      in

      (* Evaluate the function call *)
      eval_function_call_symbolic_from_inst_sig config (A.Assumed fid) inst_sig
        region_args type_args args dest cf ctx

(** Evaluate a non-local (i.e, assumed) function call such as [Box::deref]
    (auxiliary helper for [eval_statement]) *)
and eval_non_local_function_call (config : C.config) (fid : A.assumed_fun_id)
    (region_args : T.erased_region list) (type_args : T.ety list)
    (args : E.operand list) (dest : E.place) : st_cm_fun =
 fun cf ctx ->
  (* Debug *)
  log#ldebug
    (lazy
      (let type_args =
         "[" ^ String.concat ", " (List.map (ety_to_string ctx) type_args) ^ "]"
       in
       let args =
         "[" ^ String.concat ", " (List.map (operand_to_string ctx) args) ^ "]"
       in
       let dest = place_to_string ctx dest in
       "eval_non_local_function_call:\n- fid:" ^ A.show_assumed_fun_id fid
       ^ "\n- type_args: " ^ type_args ^ "\n- args: " ^ args ^ "\n- dest: "
       ^ dest));

  match config.mode with
  | C.ConcreteMode ->
      eval_non_local_function_call_concrete config fid region_args type_args
        args dest (cf Unit) ctx
  | C.SymbolicMode ->
      eval_non_local_function_call_symbolic config fid region_args type_args
        args dest cf ctx

(** Evaluate a local (i.e, not assumed) function call (auxiliary helper for
    [eval_statement]) *)
and eval_local_function_call (config : C.config) (fid : A.FunDeclId.id)
    (region_args : T.erased_region list) (type_args : T.ety list)
    (args : E.operand list) (dest : E.place) : st_cm_fun =
  match config.mode with
  | ConcreteMode ->
      eval_local_function_call_concrete config fid region_args type_args args
        dest
  | SymbolicMode ->
      eval_local_function_call_symbolic config fid region_args type_args args
        dest

(** Evaluate a statement seen as a function body *)
and eval_function_body (config : C.config) (body : A.statement) : st_cm_fun =
 fun cf ctx ->
  let cc = eval_statement config body in
  let cf_finish cf res =
    (* Note that we *don't* check the result ({!Panic}, {!Return}, etc.): we
     * delegate the check to the caller. *)
    (* Expand the symbolic values if necessary - we need to do that before
     * checking the invariants *)
    let cc = greedy_expand_symbolic_values config in
    (* Sanity check *)
    let cc = comp_check_ctx cc Inv.check_invariants in
    (* Continue *)
    cc (cf res)
  in
  (* Compose and continue *)
  comp cc cf_finish cf ctx