infer_clone/infer/src/backend/tabulation.ml

(*
 * Copyright (c) 2009 - 2013 Monoidics ltd.
 * Copyright (c) 2013 - present Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *)

(** Interprocedural footprint analysis *)

module L = Logging
module F = Format
open Utils

type splitting = {
  sub: Sil.subst;
  frame: Sil.hpred list;
  missing_pi: Sil.atom list;
  missing_sigma: Sil.hpred list;
  frame_fld : Sil.hpred list;
  missing_fld : Sil.hpred list;
  frame_typ : (Sil.exp * Sil.exp) list;
  missing_typ : (Sil.exp * Sil.exp) list;
}

type deref_error =
  | Deref_freed of Sil.res_action (** dereference a freed pointer *)
  | Deref_minusone (** dereference -1 *)
  | Deref_null of Sil.path_pos (** dereference null *)
  (** dereference a value coming from the given undefined function *)
  | Deref_undef of Procname.t * Location.t * Sil.path_pos
  | Deref_undef_exp (** dereference an undefined expression *)

type invalid_res =
  | Dereference_error of deref_error * Localise.error_desc * Paths.Path.t option (** dereference error and description *)
  | Prover_checks of Prover.check list (** the abduction prover failed some checks *)
  | Cannot_combine (** cannot combine actual pre with splitting and post *)
  | Missing_fld_not_empty (** missing_fld not empty in re-execution mode *)
  | Missing_sigma_not_empty (** missing sigma not empty in re-execution mode *)

type valid_res =
  { incons_pre_missing : bool; (** whether the actual pre is consistent with the missing part *)
    vr_pi: Sil.atom list; (** missing pi *)
    vr_sigma: Sil.hpred list; (** missing sigma *)
    vr_cons_res : (Prop.normal Prop.t * Paths.Path.t) list; (** consistent result props *)
    vr_incons_res : (Prop.normal Prop.t * Paths.Path.t) list; (** inconsistent result props *) }

(** Result of (bi)-abduction on a single spec.
    A result is invalid if no splitting was found, or if combine failed, or if we are in re - execution mode and the sigma
    part of the splitting is not empty.
    A valid result contains the missing pi ans sigma, as well as the resulting props. *)
type abduction_res =
  | Valid_res of valid_res (** valid result for a function cal *)
  | Invalid_res of invalid_res (** reason for invalid result *)

(**************** printing functions ****************)
let d_splitting split =
  L.d_strln "Actual splitting";
  L.d_increase_indent 1;
  L.d_strln "------------------------------------------------------------";
  L.d_strln "SUB = "; Prop.d_sub split.sub; L.d_ln ();
  L.d_strln "FRAME ="; Prop.d_sigma split.frame; L.d_ln ();
  L.d_strln "MISSING ="; Prop.d_pi_sigma split.missing_pi split.missing_sigma; L.d_ln ();
  L.d_strln "FRAME FLD = "; Prop.d_sigma split.frame_fld; L.d_ln ();
  L.d_strln "MISSING FLD = "; Prop.d_sigma split.missing_fld; L.d_ln ();
  if split.frame_typ <> [] then L.d_strln "FRAME TYP = "; Prover.d_typings split.frame_typ; L.d_ln ();
  if split.missing_typ <> [] then L.d_strln "MISSING TYP = "; Prover.d_typings split.missing_typ; L.d_ln ();
  L.d_strln "------------------------------------------------------------";
  L.d_decrease_indent 1

let print_results actual_pre results =
  L.d_strln "***** RESULTS FUNCTION CALL *******";
  Propset.d actual_pre (Propset.from_proplist results);
  L.d_strln "***** END RESULTS FUNCTION CALL *******"
(***************)

(** Rename the variables in the spec. *)
let spec_rename_vars pname spec =
  let prop_add_callee_suffix p =
    let f = function
      | Sil.Lvar pv ->
          Sil.Lvar (Sil.pvar_to_callee pname pv)
      | e -> e in
    Prop.prop_expmap f p in
  let jprop_add_callee_suffix = function
    | Specs.Jprop.Prop (n, p) -> Specs.Jprop.Prop (n, prop_add_callee_suffix p)
    | Specs.Jprop.Joined (n, p, jp1, jp2) -> Specs.Jprop.Joined (n, prop_add_callee_suffix p, jp1, jp2) in
  let fav = Sil.fav_new () in
  Specs.Jprop.fav_add fav spec.Specs.pre;
  IList.iter (fun (p, path) -> Prop.prop_fav_add fav p) spec.Specs.posts;
  let ids = Sil.fav_to_list fav in
  let ids' = IList.map (fun i -> (i, Ident.create_fresh Ident.kprimed)) ids in
  let ren_sub = Sil.sub_of_list (IList.map (fun (i, i') -> (i, Sil.Var i')) ids') in
  let pre' = Specs.Jprop.jprop_sub ren_sub spec.Specs.pre in
  let posts' = IList.map (fun (p, path) -> (Prop.prop_sub ren_sub p, path)) spec.Specs.posts in
  let pre'' = jprop_add_callee_suffix pre' in
  let posts'' = IList.map (fun (p, path) -> (prop_add_callee_suffix p, path)) posts' in
  { Specs.pre = pre''; Specs.posts = posts''; Specs.visited = spec.Specs.visited }

(** Find and number the specs for [proc_name], after renaming their vars, and also return the parameters *)
let spec_find_rename trace_call (proc_name : Procname.t) : (int * Prop.exposed Specs.spec) list * Sil.pvar list =
  try
    let count = ref 0 in
    let f spec =
      incr count; (!count, spec_rename_vars proc_name spec) in
    let specs, formals = Specs.get_specs_formals proc_name in
    if specs == [] then
      begin
        trace_call Specs.CallStats.CR_not_found;
        raise (Exceptions.Precondition_not_found (Localise.verbatim_desc (Procname.to_string proc_name), try assert false with Assert_failure x -> x))
      end;
    let formal_parameters =
      IList.map (fun (x, _) -> Sil.mk_pvar_callee (Mangled.from_string x) proc_name) formals in
    IList.map f specs, formal_parameters
  with Not_found -> begin
      L.d_strln ("ERROR: found no entry for procedure " ^ Procname.to_string proc_name ^ ". Give up...");
      raise (Exceptions.Precondition_not_found (Localise.verbatim_desc (Procname.to_string proc_name), try assert false with Assert_failure x -> x))
    end

(** Process a splitting coming straight from a call to the prover:
    change the instantiating substitution so that it returns primed vars,
    except for vars occurring in the missing part, where it returns
    footprint vars. *)
let process_splitting actual_pre sub1 sub2 frame missing_pi missing_sigma frame_fld missing_fld frame_typ missing_typ =
  (*
  let check_precondition () =
  let dom1 = Sil.sub_domain sub1 in
  let rng1 = Sil.sub_range sub1 in
  let dom2 = Sil.sub_domain sub2 in
  let rng2 = Sil.sub_range sub2 in
  let overlap = IList.exists (fun id -> IList.exists (Ident.equal id) dom1) dom2 in
  if overlap then begin
  L.d_str "Dom(Sub1): "; Sil.d_exp_list (IList.map (fun id -> Sil.Var id) dom1); L.d_ln ();
  L.d_str "Ran(Sub1): "; Sil.d_exp_list rng1; L.d_ln ();
  L.d_str "Dom(Sub2): "; Sil.d_exp_list (IList.map (fun id -> Sil.Var id) dom2); L.d_ln ();
  L.d_str "Ran(Sub2): "; Sil.d_exp_list rng2; L.d_ln ();
  assert false
  end in
  check_precondition ();
  *)
  let sub = Sil.sub_join sub1 sub2 in

  let sub1_inverse =
    let sub1_list = Sil.sub_to_list sub1 in
    let sub1_list' = IList.filter (function (_, Sil.Var _) -> true | _ -> false) sub1_list in
    let sub1_inverse_list = IList.map (function (id, Sil.Var id') -> (id', Sil.Var id) | _ -> assert false) sub1_list'
    in Sil.sub_of_list_duplicates sub1_inverse_list in
  let fav_actual_pre =
    let fav_sub2 = (* vars which represent expansions of fields *)
      let fav = Sil.fav_new () in
      IList.iter (Sil.exp_fav_add fav) (Sil.sub_range sub2);
      let filter id = Ident.get_stamp id = - 1 in
      Sil.fav_filter_ident fav filter;
      fav in
    let fav_pre = Prop.prop_fav actual_pre in
    Sil.ident_list_fav_add (Sil.fav_to_list fav_sub2) fav_pre;
    fav_pre in

  let fav_missing = Prop.sigma_fav (Prop.sigma_sub sub missing_sigma) in
  Prop.pi_fav_add fav_missing (Prop.pi_sub sub missing_pi);
  let fav_missing_primed =
    let filter id = Ident.is_primed id && not (Sil.fav_mem fav_actual_pre id)
    in Sil.fav_copy_filter_ident fav_missing filter in
  let fav_missing_fld = Prop.sigma_fav (Prop.sigma_sub sub missing_fld) in

  let map_var_to_pre_var_or_fresh id =
    match Sil.exp_sub sub1_inverse (Sil.Var id) with
    | Sil.Var id' ->
        if Sil.fav_mem fav_actual_pre id' || Ident.is_path id' (** a path id represents a position in the pre *)
        then Sil.Var id'
        else Sil.Var (Ident.create_fresh Ident.kprimed)
    | _ -> assert false in

  let sub_list = Sil.sub_to_list sub in
  let fav_sub_list =
    let fav_sub = Sil.fav_new () in
    IList.iter (fun (_, e) -> Sil.exp_fav_add fav_sub e) sub_list;
    Sil.fav_to_list fav_sub in
  let sub1 =
    let f id =
      if Sil.fav_mem fav_actual_pre id then (id, Sil.Var id)
      else if Ident.is_normal id then (id, map_var_to_pre_var_or_fresh id)
      else if Sil.fav_mem fav_missing_fld id then (id, Sil.Var id)
      else if Ident.is_footprint id then (id, Sil.Var id)
      else begin
        let dom1 = Sil.sub_domain sub1 in
        let rng1 = Sil.sub_range sub1 in
        let dom2 = Sil.sub_domain sub2 in
        let rng2 = Sil.sub_range sub2 in
        let vars_actual_pre = IList.map (fun id -> Sil.Var id) (Sil.fav_to_list fav_actual_pre) in
        L.d_str "fav_actual_pre: "; Sil.d_exp_list vars_actual_pre; L.d_ln ();
        L.d_str "Dom(Sub1): "; Sil.d_exp_list (IList.map (fun id -> Sil.Var id) dom1); L.d_ln ();
        L.d_str "Ran(Sub1): "; Sil.d_exp_list rng1; L.d_ln ();
        L.d_str "Dom(Sub2): "; Sil.d_exp_list (IList.map (fun id -> Sil.Var id) dom2); L.d_ln ();
        L.d_str "Ran(Sub2): "; Sil.d_exp_list rng2; L.d_ln ();
        L.d_str "Don't know about id: "; Sil.d_exp (Sil.Var id); L.d_ln ();
        assert false;
      end
    in Sil.sub_of_list (IList.map f fav_sub_list) in
  let sub2_list =
    let f id = (id, Sil.Var (Ident.create_fresh Ident.kfootprint))
    in IList.map f (Sil.fav_to_list fav_missing_primed) in
  let sub_list' =
    IList.map (fun (id, e) -> (id, Sil.exp_sub sub1 e)) sub_list in
  let sub' = Sil.sub_of_list (sub2_list @ sub_list') in
  { sub = sub'; frame = frame; missing_pi = missing_pi; missing_sigma = missing_sigma; frame_fld = frame_fld; missing_fld = missing_fld; frame_typ = frame_typ; missing_typ = missing_typ }

(** Check whether an inst represents a dereference without null check, and return the line number and path position *)
let find_dereference_without_null_check_in_inst = function
  | Sil.Iupdate (Some true, _, n, pos)
  | Sil.Irearrange (Some true, _, n, pos) -> Some (n, pos)
  | _ -> None

(** Check whether a sexp contains a dereference without null check, and return the line number and path position *)
let rec find_dereference_without_null_check_in_sexp = function
  | Sil.Eexp (_, inst) -> find_dereference_without_null_check_in_inst inst
  | Sil.Estruct (fsel, inst) ->
      let res = find_dereference_without_null_check_in_inst inst in
      if res = None then
        find_dereference_without_null_check_in_sexp_list (IList.map snd fsel)
      else res
  | Sil.Earray (_, esel, inst) ->
      let res = find_dereference_without_null_check_in_inst inst in
      if res = None then
        find_dereference_without_null_check_in_sexp_list (IList.map snd esel)
      else res
and find_dereference_without_null_check_in_sexp_list = function
  | [] -> None
  | se:: sel ->
      (match find_dereference_without_null_check_in_sexp se with
       | None -> find_dereference_without_null_check_in_sexp_list sel
       | Some x -> Some x)

(** Check dereferences implicit in the spec pre.
    In case of dereference error, return [Some(deref_error, description)], otherwise [None] *)
let check_dereferences callee_pname actual_pre sub spec_pre formal_params =
  let check_dereference e sexp =
    let e_sub = Sil.exp_sub sub e in
    let desc use_buckets deref_str =
      let error_desc =
        Errdesc.explain_dereference_as_caller_expression
          ~use_buckets
          deref_str actual_pre spec_pre e (State.get_node ()) (State.get_loc ()) formal_params in
      (L.d_strln_color Red) "found error in dereference";
      L.d_strln "spec_pre:"; Prop.d_prop spec_pre; L.d_ln();
      L.d_str "exp "; Sil.d_exp e; L.d_strln (" desc: " ^ (pp_to_string Localise.pp_error_desc error_desc));
      error_desc in
    let deref_no_null_check_pos =
      if Sil.exp_equal e_sub Sil.exp_zero then
        match find_dereference_without_null_check_in_sexp sexp with
        | Some (_, pos) -> Some pos
        | None -> None
      else None in
    if deref_no_null_check_pos != None
    then (* only report a dereference null error if we know there was a dereference without null check *)
      match deref_no_null_check_pos with
      | Some pos -> Some (Deref_null pos, desc true (Localise.deref_str_null (Some callee_pname)))
      | None -> assert false
    else
      (* Check if the dereferenced expr has the dangling uninitialized attribute. *)
      (* In that case it raise a dangling pointer dereferece *)
    if Prop.has_dangling_uninit_attribute spec_pre e then
      Some (Deref_undef_exp, desc false (Localise.deref_str_dangling (Some Sil.DAuninit)) )
    else if Sil.exp_equal e_sub Sil.exp_minus_one then Some (Deref_minusone, desc true (Localise.deref_str_dangling None))
    else match Prop.get_resource_attribute actual_pre e_sub with
      | Some (Sil.Aresource ({ Sil.ra_kind = Sil.Rrelease } as ra)) ->
          Some (Deref_freed ra, desc true (Localise.deref_str_freed ra))
      | _ ->
          (match Prop.get_undef_attribute actual_pre e_sub with
           | Some (Sil.Aundef (s, loc, pos)) ->
               Some (Deref_undef (s, loc, pos), desc false (Localise.deref_str_undef (s, loc)))
           | _ -> None) in
  let check_hpred = function
    | Sil.Hpointsto (lexp, se, _) ->
        check_dereference (Sil.root_of_lexp lexp) se
    | _ -> None in
  let deref_err_list = IList.fold_left (fun deref_errs hpred -> match check_hpred hpred with
      | Some reason -> reason :: deref_errs
      | None -> deref_errs
    ) [] (Prop.get_sigma spec_pre) in
  match deref_err_list with
  | [] -> None
  | deref_err :: _ ->
      if !Config.angelic_execution then
        (* In angelic mode, prefer to report Deref_null over other kinds of deref errors. this
         * makes sure we report a NULL_DEREFERENCE instead of a less interesting PRECONDITION_NOT_MET
         * whenever possible *)
        (* TOOD (t4893533): use this trick outside of angelic mode and in other parts of the code *)
        Some
          (try
             IList.find
               (fun err -> match err with
                  | (Deref_null _, _) -> true
                  | _ -> false )
               deref_err_list
           with Not_found -> deref_err)
      else Some deref_err

let post_process_sigma (sigma: Sil.hpred list) loc : Sil.hpred list =
  let map_inst inst = Sil.inst_new_loc loc inst in
  let do_hpred (_, _, hpred) = Sil.hpred_instmap map_inst hpred in (** update the location of instrumentations *)
  IList.map (fun hpred -> do_hpred (Prover.expand_hpred_pointer false hpred)) sigma

(** check for interprocedural path errors in the post *)
let check_path_errors_in_post caller_pname post post_path =
  let check_attr (e, att) = match att with
    | Sil.Adiv0 path_pos ->
        if Prover.check_zero e then
          let desc = Errdesc.explain_divide_by_zero e (State.get_node ()) (State.get_loc ()) in
          let new_path, path_pos_opt =
            let current_path, _ = State.get_path () in
            if Paths.Path.contains_position post_path path_pos
            then post_path, Some path_pos
            else current_path, None in (* position not found, only use the path up to the callee *)
          State.set_path new_path path_pos_opt;
          let exn = Exceptions.Divide_by_zero (desc, try assert false with Assert_failure x -> x) in
          let pre_opt = State.get_normalized_pre (fun te p -> p) (* Abs.abstract_no_symop *) in
          Reporting.log_warning caller_pname ~pre: pre_opt exn
    | _ -> () in
  IList.iter check_attr (Prop.get_all_attributes post)

(** Post process the instantiated post after the function call so that
    x.f |-> se becomes x |-> \{ f: se \}.
    Also, update any Aresource attributes to refer to the caller *)
let post_process_post
    caller_pname callee_pname loc actual_pre ((post: Prop.exposed Prop.t), post_path) =
  let actual_pre_has_freed_attribute e = match Prop.get_resource_attribute actual_pre e with
    | Some (Sil.Aresource ({ Sil.ra_kind = Sil.Rrelease })) -> true
    | _ -> false in
  let atom_update_alloc_attribute = function
    | Sil.Aneq (e , Sil.Const (Sil.Cattribute (Sil.Aresource ({ Sil.ra_res = res } as ra))))
    | Sil.Aneq (Sil.Const (Sil.Cattribute (Sil.Aresource ({ Sil.ra_res = res } as ra))), e)
      when not (ra.Sil.ra_kind = Sil.Rrelease && actual_pre_has_freed_attribute e) -> (* unless it was already freed before the call *)
        let vpath, _ = Errdesc.vpath_find post e in
        let ra' = { ra with Sil.ra_pname = callee_pname; Sil.ra_loc = loc; Sil.ra_vpath = vpath } in
        let c = Sil.Const (Sil.Cattribute (Sil.Aresource ra')) in
        Sil.Aneq (e, c)
    | a -> a in
  let prop' = Prop.replace_sigma (post_process_sigma (Prop.get_sigma post) loc) post in
  let pi' = IList.map atom_update_alloc_attribute (Prop.get_pi prop') in (* update alloc attributes to refer to the caller *)
  let post' = Prop.replace_pi pi' prop' in
  check_path_errors_in_post caller_pname post' post_path;
  post', post_path

let hpred_has_only_footprint_vars hpred =
  let fav = Sil.fav_new () in
  Sil.hpred_fav_add fav hpred;
  Sil.fav_for_all fav Ident.is_footprint

let hpred_lhs_compare hpred1 hpred2 = match hpred1, hpred2 with
  | Sil.Hpointsto(e1, _, _), Sil.Hpointsto(e2, _, _) -> Sil.exp_compare e1 e2
  | Sil.Hpointsto _, _ -> - 1
  | _, Sil.Hpointsto _ -> 1
  | hpred1, hpred2 -> Sil.hpred_compare hpred1 hpred2

(** set the inst everywhere in a sexp *)
let rec sexp_set_inst inst = function
  | Sil.Eexp (e, _) ->
      Sil.Eexp (e, inst)
  | Sil.Estruct (fsel, _) ->
      Sil.Estruct ((IList.map (fun (f, se) -> (f, sexp_set_inst inst se)) fsel), inst)
  | Sil.Earray (size, esel, _) ->
      Sil.Earray (size, IList.map (fun (e, se) -> (e, sexp_set_inst inst se)) esel, inst)

let rec fsel_star_fld fsel1 fsel2 = match fsel1, fsel2 with
  | [], fsel2 -> fsel2
  | fsel1,[] -> fsel1
  | (f1, se1):: fsel1', (f2, se2):: fsel2' ->
      (match Ident.fieldname_compare f1 f2 with
       | 0 -> (f1, sexp_star_fld se1 se2) :: fsel_star_fld fsel1' fsel2'
       | n when n < 0 -> (f1, se1) :: fsel_star_fld fsel1' fsel2
       | _ -> (f2, se2) :: fsel_star_fld fsel1 fsel2')

and array_content_star se1 se2 =
  try sexp_star_fld se1 se2 with
  | exn when exn_not_timeout exn -> se1 (* let postcondition override *)

and esel_star_fld esel1 esel2 = match esel1, esel2 with
  | [], esel2 -> (* don't know whether element is read or written in fun call with array *)
      IList.map (fun (e, se) -> (e, sexp_set_inst Sil.Inone se)) esel2
  | esel1,[] -> esel1
  | (e1, se1):: esel1', (e2, se2):: esel2' ->
      (match Sil.exp_compare e1 e2 with
       | 0 -> (e1, array_content_star se1 se2) :: esel_star_fld esel1' esel2'
       | n when n < 0 -> (e1, se1) :: esel_star_fld esel1' esel2
       | _ ->
           let se2' = sexp_set_inst Sil.Inone se2 in (* don't know whether element is read or written in fun call with array *)
           (e2, se2') :: esel_star_fld esel1 esel2')

and sexp_star_fld se1 se2 : Sil.strexp =
  (* L.d_str "sexp_star_fld "; Sil.d_sexp se1; L.d_str " "; Sil.d_sexp se2; L.d_ln (); *)
  match se1, se2 with
  | Sil.Estruct (fsel1, _), Sil.Estruct (fsel2, inst2) ->
      Sil.Estruct (fsel_star_fld fsel1 fsel2, inst2)
  | Sil.Earray (size1, esel1, _), Sil.Earray (size2, esel2, inst2) ->
      Sil.Earray (size1, esel_star_fld esel1 esel2, inst2)
  | Sil.Eexp (e1, inst1), Sil.Earray (size2, esel2, _) ->
      let esel1 = [(Sil.exp_zero, se1)] in
      Sil.Earray (size2, esel_star_fld esel1 esel2, inst1)
  | _ ->
      L.d_str "cannot star ";
      Sil.d_sexp se1; L.d_str " and "; Sil.d_sexp se2;
      L.d_ln ();
      assert false

let texp_star texp1 texp2 =
  let rec ftal_sub ftal1 ftal2 = match ftal1, ftal2 with
    | [], _ -> true
    | _, [] -> false
    | (f1, t1, a1):: ftal1', (f2, t2, a2):: ftal2' ->
        begin match Ident.fieldname_compare f1 f2 with
          | n when n < 0 -> false
          | 0 -> ftal_sub ftal1' ftal2'
          | _ -> ftal_sub ftal1 ftal2' end in
  let typ_star t1 t2 = match t1, t2 with
    | Sil.Tstruct (ftal1, sftal1, csu1, _, _, _, _), Sil.Tstruct (ftal2, sftal2, csu2, _, _, _, _) when csu1 = csu2 ->
        if ftal_sub ftal1 ftal2 then t2 else t1
    | _ -> t1 in
  match texp1, texp2 with
  | Sil.Sizeof (t1, st1), Sil.Sizeof (t2, st2) -> Sil.Sizeof (typ_star t1 t2, Sil.Subtype.join st1 st2)
  | _ -> texp1

let hpred_star_fld (hpred1 : Sil.hpred) (hpred2 : Sil.hpred) : Sil.hpred =
  match hpred1, hpred2 with
  | Sil.Hpointsto(e1, se1, t1), Sil.Hpointsto(_, se2, t2) ->
      (* L.d_str "hpred_star_fld t1: "; Sil.d_texp_full t1; L.d_str " t2: "; Sil.d_texp_full t2;
         L.d_str " se1: "; Sil.d_sexp se1; L.d_str " se2: "; Sil.d_sexp se2; L.d_ln (); *)
      Sil.Hpointsto(e1, sexp_star_fld se1 se2, texp_star t1 t2)
  | _ -> assert false

(** Implementation of [*] for the field-splitting model *)
let sigma_star_fld (sigma1 : Sil.hpred list) (sigma2 : Sil.hpred list) : Sil.hpred list =
  let sigma1 = IList.stable_sort hpred_lhs_compare sigma1 in
  let sigma2 = IList.stable_sort hpred_lhs_compare sigma2 in
  (* L.out "@.@. computing %a@.STAR @.%a@.@." pp_sigma sigma1 pp_sigma sigma2; *)
  let rec star sg1 sg2 : Sil.hpred list =
    match sg1, sg2 with
    | [], sigma2 -> []
    | sigma1,[] -> sigma1
    | hpred1:: sigma1', hpred2:: sigma2' ->
        begin
          match hpred_lhs_compare hpred1 hpred2 with
          | 0 -> hpred_star_fld hpred1 hpred2 :: star sigma1' sigma2'
          | n when n < 0 -> hpred1 :: star sigma1' sg2
          | _ -> star sg1 sigma2'
        end
  in
  try star sigma1 sigma2
  with exn when exn_not_timeout exn ->
    L.d_str "cannot star ";
    Prop.d_sigma sigma1; L.d_str " and "; Prop.d_sigma sigma2;
    L.d_ln ();
    raise (Prop.Cannot_star (try assert false with Assert_failure x -> x))

let hpred_typing_lhs_compare hpred1 (e2, te2) = match hpred1 with
  | Sil.Hpointsto(e1, _, _) -> Sil.exp_compare e1 e2
  | _ -> - 1

let hpred_star_typing (hpred1 : Sil.hpred) (e2, te2) : Sil.hpred =
  match hpred1 with
  | Sil.Hpointsto(e1, se1, te1) -> Sil.Hpointsto (e1, se1, te2)
  | _ -> assert false

(** Implementation of [*] between predicates and typings *)
let sigma_star_typ (sigma1 : Sil.hpred list) (typings2 : (Sil.exp * Sil.exp) list) : Sil.hpred list =
  if !Config.Experiment.activate_subtyping_in_cpp || !Config.curr_language = Config.Java then
    begin
      let typing_lhs_compare (e1, _) (e2, _) = Sil.exp_compare e1 e2 in
      let sigma1 = IList.stable_sort hpred_lhs_compare sigma1 in
      let typings2 = IList.stable_sort typing_lhs_compare typings2 in
      let rec star sg1 typ2 : Sil.hpred list =
        match sg1, typ2 with
        | [], _ -> []
        | sigma1,[] -> sigma1
        | hpred1:: sigma1', typing2:: typings2' ->
            begin
              match hpred_typing_lhs_compare hpred1 typing2 with
              | 0 -> hpred_star_typing hpred1 typing2 :: star sigma1' typings2'
              | n when n < 0 -> hpred1 :: star sigma1' typ2
              | _ -> star sg1 typings2'
            end in
      try star sigma1 typings2
      with exn when exn_not_timeout exn ->
        L.d_str "cannot star ";
        Prop.d_sigma sigma1; L.d_str " and "; Prover.d_typings typings2;
        L.d_ln ();
        raise (Prop.Cannot_star (try assert false with Assert_failure x -> x))
    end
  else sigma1

(** [prop_footprint_add_pi_sigma_starfld_sigma prop pi sigma missing_fld] extends the footprint of [prop] with [pi,sigma] and extends the fields of |-> with [missing_fld] *)
let prop_footprint_add_pi_sigma_starfld_sigma (prop : 'a Prop.t) pi_new sigma_new missing_fld missing_typ : Prop.normal Prop.t option =
  let rec extend_sigma current_sigma new_sigma = match new_sigma with
    | [] -> Some current_sigma
    | hpred :: new_sigma' ->
        let fav = Prop.sigma_fav [hpred] in
        (* TODO (t4893479): make this check less angelic *)
        if Sil.fav_exists fav
            (fun id -> not (Ident.is_footprint id) && not !Config.angelic_execution)
        then begin
          L.d_warning "found hpred with non-footprint variable, dropping the spec"; L.d_ln (); Sil.d_hpred hpred; L.d_ln ();
          None
        end
        else extend_sigma (hpred :: current_sigma) new_sigma' in
  let rec extend_pi current_pi new_pi = match new_pi with
    | [] -> current_pi
    | a :: new_pi' ->
        let fav = Prop.pi_fav [a] in
        if Sil.fav_exists fav (fun id -> not (Ident.is_footprint id))
        then begin
          L.d_warning "dropping atom with non-footprint variable"; L.d_ln (); Sil.d_atom a; L.d_ln ();
          extend_pi current_pi new_pi'
        end
        else extend_pi (a :: current_pi) new_pi' in
  let foot_pi' = extend_pi (Prop.get_pi_footprint prop) pi_new in
  match extend_sigma (Prop.get_sigma_footprint prop) sigma_new with
  | None -> None
  | Some sigma' ->
      let foot_sigma' = sigma_star_fld sigma' missing_fld in
      let foot_sigma'' = sigma_star_typ foot_sigma' missing_typ in
      let pi' = pi_new @ Prop.get_pi prop in
      let prop' = Prop.replace_sigma_footprint foot_sigma'' (Prop.replace_pi_footprint foot_pi' prop) in
      let prop'' = Prop.replace_pi pi' prop' in
      Some (Prop.normalize prop'')

(** Check if the attribute change is a mismatch between a kind of allocation and a different kind of deallocation *)
let check_attr_dealloc_mismatch att_old att_new = match att_old, att_new with
  | Sil.Aresource ({ Sil.ra_kind = Sil.Racquire; Sil.ra_res = Sil.Rmemory mk_old } as ra_old),
    Sil.Aresource ({ Sil.ra_kind = Sil.Rrelease; Sil.ra_res = Sil.Rmemory mk_new } as ra_new)
    when Sil.mem_kind_compare mk_old mk_new <> 0 ->
      let desc = Errdesc.explain_allocation_mismatch ra_old ra_new in
      raise (Exceptions.Deallocation_mismatch (desc, try assert false with Assert_failure x -> x))
  | _ -> ()

(** [prop_copy_footprint p1 p2] copies the footprint and pure part of [p1] into [p2] *)
let prop_copy_footprint_pure p1 p2 =
  let p2' = Prop.replace_sigma_footprint (Prop.get_sigma_footprint p1) (Prop.replace_pi_footprint (Prop.get_pi_footprint p1) p2) in
  let pi2 = Prop.get_pi p2' in
  let pi2_attr, pi2_noattr = IList.partition Prop.atom_is_attribute pi2 in
  let res_noattr = Prop.replace_pi (Prop.get_pure p1 @ pi2_noattr) p2' in
  let replace_attr prop atom = (* call replace_atom_attribute which deals with existing attibutes *)
    (** if [atom] represents an attribute [att], add the attribure to [prop] *)
    match Prop.atom_get_exp_attribute atom with
    | None -> prop
    | Some (exp, att) ->
        Prop.add_or_replace_exp_attribute_check_changed check_attr_dealloc_mismatch prop exp att in
  IList.fold_left replace_attr (Prop.normalize res_noattr) pi2_attr

(** check if an expression is an exception *)
let exp_is_exn = function
  | Sil.Const Sil.Cexn _ -> true
  | _ -> false

(** check if a prop is an exception *)
let prop_is_exn pname prop =
  let ret_pvar = Sil.Lvar (Sil.get_ret_pvar pname) in
  let is_exn = function
    | Sil.Hpointsto (e1, Sil.Eexp(e2, _), _) when Sil.exp_equal e1 ret_pvar ->
        exp_is_exn e2
    | _ -> false in
  IList.exists is_exn (Prop.get_sigma prop)

(** when prop is an exception, return the exception name *)
let prop_get_exn_name pname prop =
  let ret_pvar = Sil.Lvar (Sil.get_ret_pvar pname) in
  let exn_name = ref (Mangled.from_string "") in
  let find_exn_name e =
    let do_hpred = function
      | Sil.Hpointsto (e1, _, Sil.Sizeof(Sil.Tstruct (_, _, _, Some name, _, _, _), _)) when Sil.exp_equal e1 e ->
          exn_name := name
      | _ -> () in
    IList.iter do_hpred (Prop.get_sigma prop) in
  let find_ret () =
    let do_hpred = function
      | Sil.Hpointsto (e1, Sil.Eexp(Sil.Const (Sil.Cexn e2), _), _) when Sil.exp_equal e1 ret_pvar ->
          find_exn_name e2
      | _ -> () in
    IList.iter do_hpred (Prop.get_sigma prop) in
  find_ret ();
  !exn_name

(** search in prop for some assignment of global errors *)
let lookup_global_errors prop =
  let rec search_error = function
    | [] -> None
    | Sil.Hpointsto (Sil.Lvar var, Sil.Eexp (Sil.Const (Sil.Cstr str), _), _) :: tl
      when Sil.pvar_equal var Sil.global_error -> Some (Mangled.from_string str)
    | _ :: tl -> search_error tl in
  search_error (Prop.get_sigma prop)

(** set a prop to an exception sexp *)
let prop_set_exn pname prop se_exn =
  let ret_pvar = Sil.Lvar (Sil.get_ret_pvar pname) in
  let map_hpred = function
    | Sil.Hpointsto (e, _, t) when Sil.exp_equal e ret_pvar ->
        Sil.Hpointsto(e, se_exn, t)
    | hpred -> hpred in
  let sigma' = IList.map map_hpred (Prop.get_sigma prop) in
  Prop.normalize (Prop.replace_sigma sigma' prop)

(** Include a subtrace for a procedure call if the callee is not a model. *)
let include_subtrace callee_pname =
  Specs.get_origin callee_pname <> Specs.Models

(** combine the spec's post with a splitting and actual precondition *)
let combine
    cfg ret_ids (posts: ('a Prop.t * Paths.Path.t) list)
    actual_pre path_pre split
    caller_pdesc callee_pname loc =
  let caller_pname = Cfg.Procdesc.get_proc_name caller_pdesc in
  let new_footprint_pi = Prop.pi_sub split.sub split.missing_pi in
  let new_footprint_sigma = Prop.sigma_sub split.sub split.missing_sigma in
  let new_frame_fld = Prop.sigma_sub split.sub split.frame_fld in
  let new_frame_typ = IList.map (fun (e, te) -> Sil.exp_sub split.sub e, Sil.exp_sub split.sub te) split.frame_typ in
  let new_missing_typ = IList.map (fun (e, te) -> Sil.exp_sub split.sub e, Sil.exp_sub split.sub te) split.missing_typ in
  let new_missing_fld =
    let sigma = Prop.sigma_sub split.sub split.missing_fld in
    let filter hpred =
      if not (hpred_has_only_footprint_vars hpred) then
        begin
          L.d_warning "Missing fields hpred has non-footprint vars: "; Sil.d_hpred hpred; L.d_ln ();
          false
        end
      else match hpred with
        | Sil.Hpointsto(Sil.Var id, _, _) -> true
        | Sil.Hpointsto(Sil.Lvar pvar, _, _) -> Sil.pvar_is_global pvar
        | _ ->
            L.d_warning "Missing fields in complex pred: "; Sil.d_hpred hpred; L.d_ln ();
            false in
    IList.filter filter sigma in
  let instantiated_frame = Prop.sigma_sub split.sub split.frame in
  let instantiated_post =
    let posts' =
      if !Config.footprint && posts = []
      then (* in case of divergence, produce a prop *)
        (* with updated footprint and inconsistent current *)
        [(Prop.replace_pi [Sil.Aneq (Sil.exp_zero, Sil.exp_zero)] Prop.prop_emp, path_pre)]
      else
        IList.map
          (fun (p, path_post) ->
             (p,
              Paths.Path.add_call
                (include_subtrace callee_pname)
                path_pre
                callee_pname
                path_post))
          posts in
    IList.map
      (fun (p, path) ->
         (post_process_post
            caller_pname callee_pname loc actual_pre (Prop.prop_sub split.sub p, path)))
      posts' in
  L.d_increase_indent 1;
  L.d_strln "New footprint:"; Prop.d_pi_sigma new_footprint_pi new_footprint_sigma; L.d_ln ();
  L.d_strln "Frame fld:"; Prop.d_sigma new_frame_fld; L.d_ln ();
  if new_frame_typ <> [] then L.d_strln "Frame typ:"; Prover.d_typings new_frame_typ; L.d_ln ();
  L.d_strln "Missing fld:"; Prop.d_sigma new_missing_fld; L.d_ln ();
  if new_frame_typ <> [] then L.d_strln "Missing typ:"; Prover.d_typings new_missing_typ; L.d_ln ();
  L.d_strln "Instantiated frame:"; Prop.d_sigma instantiated_frame; L.d_ln ();
  L.d_strln "Instantiated post:"; Propgraph.d_proplist Prop.prop_emp (IList.map fst instantiated_post);
  L.d_decrease_indent 1; L.d_ln ();
  let compute_result post_p =
    let post_p' =
      let post_sigma = sigma_star_fld (Prop.get_sigma post_p) new_frame_fld in
      let post_sigma' = sigma_star_typ post_sigma new_frame_typ in
      Prop.replace_sigma post_sigma' post_p in
    let post_p1 = Prop.prop_sigma_star (prop_copy_footprint_pure actual_pre post_p') instantiated_frame in

    let handle_null_case_analysis sigma =
      let id_assigned_to_null id =
        let filter = function
          | Sil.Aeq (Sil.Var id', Sil.Const (Sil.Cint i)) ->
              Ident.equal id id' && Sil.Int.isnull i
          | _ -> false in
        IList.exists filter new_footprint_pi in
      let f (e, inst_opt) = match e, inst_opt with
        | Sil.Var id, Some inst when id_assigned_to_null id ->
            let inst' = Sil.inst_set_null_case_flag inst in
            (e, Some inst')
        | _ -> (e, inst_opt) in
      Sil.hpred_list_expmap f sigma in

    let post_p2 =
      let post_p1_sigma = Prop.get_sigma post_p1 in
      let post_p1_sigma' = handle_null_case_analysis post_p1_sigma in
      let post_p1' = Prop.replace_sigma post_p1_sigma' post_p1 in
      Prop.normalize (Prop.replace_pi (Prop.get_pi post_p1 @ new_footprint_pi) post_p1') in

    let post_p3 = (** replace [result|callee] with an aux variable dedicated to this proc *)
      let callee_ret_pvar =
        Sil.Lvar (Sil.pvar_to_callee callee_pname (Sil.get_ret_pvar callee_pname)) in
      match Prop.prop_iter_create post_p2 with
      | None -> post_p2
      | Some iter ->
          let filter = function
            | Sil.Hpointsto (e, se, t) when Sil.exp_equal e callee_ret_pvar -> Some ()
            | _ -> None in
          match Prop.prop_iter_find iter filter with
          | None -> post_p2
          | Some iter' ->
              match fst (Prop.prop_iter_current iter') with
              | Sil.Hpointsto (e, Sil.Eexp (e', inst), t) when exp_is_exn e' -> (* resuls is an exception: set in caller *)
                  let p = Prop.prop_iter_remove_curr_then_to_prop iter' in
                  prop_set_exn caller_pname p (Sil.Eexp (e', inst))
              | Sil.Hpointsto (e, Sil.Eexp (e', inst), t) when IList.length ret_ids = 1 ->
                  let p = Prop.prop_iter_remove_curr_then_to_prop iter' in
                  Prop.conjoin_eq e' (Sil.Var (IList.hd ret_ids)) p
              | Sil.Hpointsto (e, Sil.Estruct (ftl, _), t)
                when IList.length ftl = IList.length ret_ids ->
                  let rec do_ftl_ids p = function
                    | [], [] -> p
                    | (f, Sil.Eexp (e', inst')):: ftl', ret_id:: ret_ids' ->
                        let p' = Prop.conjoin_eq e' (Sil.Var ret_id) p in
                        do_ftl_ids p' (ftl', ret_ids')
                    | _ -> p in
                  let p = Prop.prop_iter_remove_curr_then_to_prop iter' in
                  do_ftl_ids p (ftl, ret_ids)
              | Sil.Hpointsto (e, _, t) -> (** returning nothing or unexpected sexp, turning into nondet *)
                  Prop.prop_iter_remove_curr_then_to_prop iter'
              | _ -> assert false in
    let post_p4 =
      if !Config.footprint
      then
        prop_footprint_add_pi_sigma_starfld_sigma post_p3 new_footprint_pi new_footprint_sigma new_missing_fld new_missing_typ
      else Some post_p3 in
    post_p4 in
  let _results = IList.map (fun (p, path) -> (compute_result p, path)) instantiated_post in
  if IList.exists (fun (x, _) -> x = None) _results then (* at least one combine failed *)
    None
  else
    let results = IList.map (function (Some x, path) -> (x, path) | (None, _) -> assert false) _results in
    print_results actual_pre (IList.map fst results);
    Some results

(** Construct the actual precondition: add to the current state a copy
    of the (callee's) formal parameters instantiated with the actual
    parameters. *)
let mk_actual_precondition prop actual_params formal_params =
  let formals_actuals =
    let rec comb fpars apars = match fpars, apars with
      | f:: fpars', a:: apars' -> (f, a) :: comb fpars' apars'
      | [], _ ->
          if apars != [] then
            (let str = "more actual pars than formal pars in fun call (" ^ string_of_int (IList.length actual_params) ^ " vs " ^ string_of_int (IList.length formal_params) ^ ")" in
             L.d_warning str; L.d_ln ());
          []
      | _:: _,[] -> raise (Exceptions.Wrong_argument_number (try assert false with Assert_failure x -> x)) in
    comb formal_params actual_params in
  let mk_instantiation (formal_var, (actual_e, actual_t)) =
    Prop.mk_ptsto (Sil.Lvar formal_var) (Sil.Eexp (actual_e, Sil.inst_actual_precondition)) (Sil.Sizeof (actual_t, Sil.Subtype.exact)) in
  let instantiated_formals = IList.map mk_instantiation formals_actuals in
  let actual_pre = Prop.prop_sigma_star prop instantiated_formals in
  Prop.normalize actual_pre

(** Check if actual_pre * missing_footprint |- false *)
let inconsistent_actualpre_missing actual_pre split_opt =
  match split_opt with
  | Some split ->
      let norm_missing_pi = Prop.pi_sub split.sub split.missing_pi in
      let norm_missing_sigma = Prop.sigma_sub split.sub split.missing_sigma in
      let prop'= Prop.normalize (Prop.prop_sigma_star actual_pre norm_missing_sigma) in
      let prop''= IList.fold_left Prop.prop_atom_and prop' norm_missing_pi in
      Prover.check_inconsistency prop''
  | None -> false

(* Collect the taint/untain info on the pi part *)
(* TODO (t9199155): this be done with a single traversal of the list of atoms/combined with
   intersection_taint_untaint to be much more efficient *)
let rec get_taint_untaint pi =
  let get_att_exp p e (t,u) atom =
    match Prop.get_taint_attribute p e with
    | Some(Sil.Ataint _) ->
        L.d_str "   ---->Found TAINTED exp: "; Sil.d_exp e; L.d_ln ();
        ((e, atom)::t, u)
    | Some(Sil.Auntaint) ->
        L.d_str "   ---->Found UNTAINTED exp: "; Sil.d_exp e; L.d_ln ();
        (t, (e, atom)::u)
    | _ -> (t,u) in
  match pi with
  | [] -> ([],[])
  | (Sil.Aneq (e1, e2) as atom) :: pi' ->
      let (t, u) = get_taint_untaint pi' in
      let p = Prop.replace_pi [atom] Prop.prop_emp in
      let (t',u') = get_att_exp p e1 (t,u) atom in
      get_att_exp p e2 (t',u') atom
  | _ :: pi' -> get_taint_untaint pi'

(* perform the taint analysis check by comparing in a function call the
   actual calling state and the missing pi computed by abduction *)
let do_taint_check caller_pname callee_pname calling_prop missing_pi sub prop =
  let rec intersection_taint_untaint taint untaint acc =
    match taint with
    | [] -> acc
    | (e1, atom_taint) :: taint' ->
        let acc' =
          try
            let (e2, atom_untaint) =
              IList.find (fun (e2, _) -> Sil.exp_equal e1 e2) untaint in
            (e1, atom_taint, atom_untaint) :: acc
          with Not_found -> acc in
        intersection_taint_untaint taint' untaint acc' in
  let combined_calling_prop =
    Prop.replace_pi ((Prop.get_pi calling_prop) @ missing_pi) calling_prop in
  let sub_combined_calling_prop = Prop.prop_sub sub combined_calling_prop in
  let taint_set, untaint_set = get_taint_untaint (Prop.get_pi sub_combined_calling_prop) in
  L.d_str "Actual pre combined with missing pi: "; Prop.d_prop sub_combined_calling_prop; L.d_ln();
  L.d_str "Taint set: "; Sil.d_exp_list (fst (IList.split taint_set)); L.d_ln ();
  L.d_str "Untaint set: "; Sil.d_exp_list (fst (IList.split untaint_set)); L.d_ln ();
  let report_taint_error (e, _, _) =
    L.d_str "Taint error detected!"; L.d_ln();
    let e' = match Errdesc.find_pvar_with_exp prop e with
      | Some (pv, _) -> Sil.Lvar pv
      | None -> e in
    let tainting_fun = match Prop.get_taint_attribute prop e with
      | Some (Sil.Ataint tf) -> tf
      | _ -> Procname.empty  (* by definition of e, we should not get to this case *) in
    let err_desc = Errdesc.explain_tainted_value_reaching_sensitive_function e' tainting_fun
        callee_pname (State.get_loc ()) in
    let exn =
      Exceptions.Tainted_value_reaching_sensitive_function
        (err_desc, try assert false with Assert_failure x -> x) in
    Reporting.log_warning caller_pname exn in
  match intersection_taint_untaint taint_set untaint_set [] with
  | [] ->
      L.d_str "NO taint error detected"; L.d_ln();
      missing_pi
  | taint_errors ->
      IList.iter report_taint_error taint_errors;
      (* get a version of [missing_pi] whose var names match names in taint_errors *)
      let missing_pi_sub =
        Prop.get_pi (Prop.prop_sub sub (Prop.replace_pi missing_pi Prop.prop_emp)) in
      (* filter out UNTAINT(e) atoms from [missing_pi] such that we have already reported a taint
         error on e. without doing this, we will get PRECONDITION_NOT_MET (and failed spec
         inference), which is bad. instead, what this does is effectively assume that the UNTAINT(e)
         precondition was met, and contine with the analysis under this assumption. this makes sense
         because we are reporting the taint error, but propagating a *safe* postcondition w.r.t to
         tainting. *)
      IList.filter
        (fun atom -> not
            (IList.exists
               (fun (_, _, atom_untaint) -> Sil.atom_equal atom atom_untaint)
               taint_errors))
        missing_pi_sub

let class_cast_exn pname_opt texp1 texp2 exp ml_location =
  let desc = Errdesc.explain_class_cast_exception pname_opt texp1 texp2 exp (State.get_node ()) (State.get_loc ()) in
  Exceptions.Class_cast_exception (desc, ml_location)

let raise_cast_exception ml_location pname_opt texp1 texp2 exp =
  let exn = class_cast_exn pname_opt texp1 texp2 exp ml_location in
  raise exn

let get_check_exn check callee_pname loc ml_location = match check with
  | Prover.Bounds_check ->
      let desc = Localise.desc_precondition_not_met (Some Localise.Pnm_bounds) callee_pname loc in
      Exceptions.Precondition_not_met (desc, ml_location)
  | Prover.Class_cast_check (texp1, texp2, exp) ->
      class_cast_exn (Some callee_pname) texp1 texp2 exp ml_location

let check_uninitialize_dangling_deref callee_pname actual_pre sub formal_params props =
  IList.iter (fun (p, _ ) ->
      match check_dereferences callee_pname actual_pre sub p formal_params with
      | Some (Deref_undef_exp, desc) ->
          raise (Exceptions.Dangling_pointer_dereference (Some Sil.DAuninit, desc, try assert false with Assert_failure x -> x))
      | _ -> ()) props

(** Perform symbolic execution for a single spec *)
let exe_spec
    tenv cfg ret_ids (n, nspecs) caller_pdesc callee_pname loc prop path_pre
    (spec : Prop.exposed Specs.spec) actual_params formal_params : abduction_res =
  let caller_pname = Cfg.Procdesc.get_proc_name caller_pdesc in
  let posts =
    match ret_ids with
    | [ret_id] when !Config.idempotent_getters && !Config.curr_language = Config.Java ->
        (* if we have seen a previous call to the same function, only use specs whose return value
           is consistent with constraints on the return value of the previous call w.r.t to nullness.
           meant to eliminate false NPE warnings from the common "if (get() != null) get().something()"
           pattern *)
        let last_call_ret_non_null =
          IList.exists
            (fun (exp, attr) ->
               match attr with
               | Sil.Aretval pname when Procname.equal callee_pname pname ->
                   Prover.check_disequal prop exp Sil.exp_zero
               | _ -> false)
            (Prop.get_all_attributes prop) in
        if last_call_ret_non_null then
          let returns_null prop =
            IList.exists
              (function
                | Sil.Hpointsto (Sil.Lvar pvar, Sil.Eexp (e, _), _) when Sil.pvar_is_return pvar ->
                    Prover.check_equal (Prop.normalize prop) e Sil.exp_zero
                | _ -> false)
              (Prop.get_sigma prop) in
          IList.filter (fun (prop, _) -> not (returns_null prop)) spec.Specs.posts
        else spec.Specs.posts
    | _ -> spec.Specs.posts in
  let actual_pre = mk_actual_precondition prop actual_params formal_params in
  let spec_pre = Specs.Jprop.to_prop spec.Specs.pre in
  L.d_strln ("EXECUTING SPEC " ^ string_of_int n ^ "/" ^ string_of_int nspecs);
  L.d_strln "ACTUAL PRECONDITION =";
  L.d_increase_indent 1; Prop.d_prop actual_pre; L.d_decrease_indent 1; L.d_ln ();
  L.d_strln "SPEC =";
  L.d_increase_indent 1; Specs.d_spec spec; L.d_decrease_indent 1; L.d_ln ();
  SymOp.pay(); (* pay one symop *)
  match Prover.check_implication_for_footprint caller_pname tenv actual_pre spec_pre with
  | Prover.ImplFail checks -> Invalid_res (Prover_checks checks)
  | Prover.ImplOK (checks, sub1, sub2, frame, missing_pi, missing_sigma, frame_fld, missing_fld, frame_typ, missing_typ) ->
      let log_check_exn check =
        let exn = get_check_exn check callee_pname loc (try assert false with Assert_failure x -> x) in
        Reporting.log_warning caller_pname exn in
      let do_split () =
        let missing_pi' =
          if !Config.taint_analysis then
            do_taint_check caller_pname callee_pname actual_pre missing_pi sub2 prop
          else missing_pi in
        let split = process_splitting actual_pre sub1 sub2 frame missing_pi' missing_sigma frame_fld missing_fld frame_typ missing_typ in
        d_splitting split; L.d_ln ();
        let norm_missing_pi = Prop.pi_sub split.sub split.missing_pi in
        let norm_missing_sigma = Prop.sigma_sub split.sub split.missing_sigma in
        (split, norm_missing_pi, norm_missing_sigma) in
      let report_valid_res split norm_missing_pi norm_missing_sigma =
        match combine
                cfg ret_ids posts
                actual_pre path_pre split
                caller_pdesc callee_pname loc with
        | None -> Invalid_res Cannot_combine
        | Some results ->
            (* After combining we check that we have not added a points-to of initialized variables.*)
            check_uninitialize_dangling_deref callee_pname actual_pre split.sub formal_params results;
            let inconsistent_results, consistent_results =
              IList.partition (fun (p, _) -> Prover.check_inconsistency p) results in
            let incons_pre_missing = inconsistent_actualpre_missing actual_pre (Some split) in
            Valid_res { incons_pre_missing = incons_pre_missing;
                        vr_pi = norm_missing_pi;
                        vr_sigma = norm_missing_sigma;
                        vr_cons_res = consistent_results;
                        vr_incons_res = inconsistent_results } in
      begin
        IList.iter log_check_exn checks;
        let subbed_pre = (Prop.prop_sub sub1 actual_pre) in
        match check_dereferences callee_pname subbed_pre sub2 spec_pre formal_params with
        | Some (Deref_undef _, _) when !Config.angelic_execution ->
            let (split, norm_missing_pi, norm_missing_sigma) = do_split () in
            report_valid_res split norm_missing_pi norm_missing_sigma
        | Some (deref_error, desc) ->
            let rec join_paths = function
              | [] -> None
              | (_, p):: l ->
                  (match join_paths l with
                   | None -> Some p
                   | Some p' -> Some (Paths.Path.join p p')) in
            let pjoin = join_paths posts in (* join the paths from the posts *)
            Invalid_res (Dereference_error (deref_error, desc, pjoin))
        | None ->
            let (split, norm_missing_pi, norm_missing_sigma) = do_split () in
            (* check if a missing_fld hpred is about a hidden field *)
            let hpred_missing_hidden = function
              | Sil.Hpointsto (_, Sil.Estruct ([(fld, _)], _), _) -> Ident.fieldname_is_hidden fld
              | _ -> false in
            (* missing fields minus hidden fields *)
            let missing_fld_nohidden =
              IList.filter (fun hp -> not (hpred_missing_hidden hp)) missing_fld in
            if !Config.footprint = false && norm_missing_sigma != [] then
              begin
                L.d_strln "Implication error: missing_sigma not empty in re-execution";
                Invalid_res Missing_sigma_not_empty
              end
            else if !Config.footprint = false && missing_fld_nohidden != [] then
              begin
                L.d_strln "Implication error: missing_fld not empty in re-execution";
                Invalid_res Missing_fld_not_empty
              end
            else report_valid_res split norm_missing_pi norm_missing_sigma
      end

let remove_constant_string_class prop =
  let filter = function
    | Sil.Hpointsto (Sil.Const (Sil.Cstr _ | Sil.Cclass _), _, _) -> false
    | _ -> true in
  let sigma = IList.filter filter (Prop.get_sigma prop) in
  let sigmafp = IList.filter filter (Prop.get_sigma_footprint prop) in
  let prop' = Prop.replace_sigma_footprint sigmafp (Prop.replace_sigma sigma prop) in
  Prop.normalize prop'

(** existentially quantify the path identifier generated by the prover to keep track of expansions of lhs paths
    and remove pointsto's whose lhs is a constant string *)
let quantify_path_idents_remove_constant_strings (prop: Prop.normal Prop.t) : Prop.normal Prop.t =
  let fav = Prop.prop_fav prop in
  Sil.fav_filter_ident fav Ident.is_path;
  remove_constant_string_class (Prop.exist_quantify fav prop)

(** Strengthen the footprint by adding pure facts from the current part *)
let prop_pure_to_footprint (p: 'a Prop.t) : Prop.normal Prop.t =
  let is_footprint_atom_not_attribute a =
    not (Prop.atom_is_attribute a)
    &&
    let a_fav = Sil.atom_fav a in
    Sil.fav_for_all a_fav Ident.is_footprint in
  let pure = Prop.get_pure p in
  let new_footprint_atoms = IList.filter is_footprint_atom_not_attribute pure in
  if new_footprint_atoms == []
  then p
  else (** add pure fact to footprint *)
    Prop.normalize (Prop.replace_pi_footprint (Prop.get_pi_footprint p @ new_footprint_atoms) p)

(** check whether 0|->- occurs in sigma *)
let sigma_has_null_pointer sigma =
  let hpred_null_pointer = function
    | Sil.Hpointsto (e, _, _) ->
        Sil.exp_equal e Sil.exp_zero
    | _ -> false in
  IList.exists hpred_null_pointer sigma

(** post-process the raw result of a function call *)
let exe_call_postprocess tenv ret_ids trace_call callee_pname loc initial_prop results =
  let filter_valid_res = function
    | Invalid_res _ -> false
    | Valid_res _ -> true in
  let valid_res0, invalid_res0 =
    IList.partition filter_valid_res results in
  let valid_res =
    IList.map (function Valid_res cr -> cr | Invalid_res _ -> assert false) valid_res0 in
  let invalid_res =
    IList.map (function Valid_res cr -> assert false | Invalid_res ir -> ir) invalid_res0 in
  let valid_res_miss_pi, valid_res_no_miss_pi =
    IList.partition (fun vr -> vr.vr_pi != []) valid_res in
  let valid_res_incons_pre_missing, valid_res_cons_pre_missing =
    IList.partition (fun vr -> vr.incons_pre_missing) valid_res in
  let deref_errors = IList.filter (function Dereference_error _ -> true | _ -> false) invalid_res in
  let print_pi pi =
    L.d_str "pi: "; Prop.d_pi pi; L.d_ln () in
  let call_desc kind_opt = Localise.desc_precondition_not_met kind_opt callee_pname loc in
  let res_with_path_idents =
    if !Config.footprint then
      begin
        if valid_res_cons_pre_missing == [] then (* no valid results where actual pre and missing are consistent *)
          begin
            if deref_errors <> [] then (* dereference error detected *)
              let extend_path path_opt path_pos_opt = match path_opt with
                | None -> ()
                | Some path_post ->
                    let old_path, _ = State.get_path () in
                    let new_path = Paths.Path.add_call (include_subtrace callee_pname) old_path callee_pname path_post in
                    State.set_path new_path path_pos_opt in
              match IList.hd deref_errors with
              | Dereference_error (Deref_minusone, desc, path_opt) ->
                  trace_call Specs.CallStats.CR_not_met;
                  extend_path path_opt None;
                  raise (Exceptions.Dangling_pointer_dereference (Some Sil.DAminusone, desc, try assert false with Assert_failure x -> x))
              | Dereference_error (Deref_undef_exp, desc, path_opt) ->
                  trace_call Specs.CallStats.CR_not_met;
                  extend_path path_opt None;
                  raise (Exceptions.Dangling_pointer_dereference (Some Sil.DAuninit, desc, try assert false with Assert_failure x -> x))
              | Dereference_error (Deref_null pos, desc, path_opt) ->
                  trace_call Specs.CallStats.CR_not_met;
                  extend_path path_opt (Some pos);
                  if Localise.is_parameter_not_null_checked_desc desc then
                    raise (Exceptions.Parameter_not_null_checked (desc, try assert false with Assert_failure x -> x))
                  else if Localise.is_field_not_null_checked_desc desc then
                    raise (Exceptions.Field_not_null_checked (desc, try assert false with Assert_failure x -> x))
                  else raise (Exceptions.Null_dereference (desc, try assert false with Assert_failure x -> x))
              | Dereference_error (Deref_freed ra, desc, path_opt) ->
                  trace_call Specs.CallStats.CR_not_met;
                  extend_path path_opt None;
                  raise (Exceptions.Use_after_free (desc, try assert false with Assert_failure x -> x))
              | Dereference_error (Deref_undef (s, loc, pos), desc, path_opt) ->
                  trace_call Specs.CallStats.CR_not_met;
                  extend_path path_opt (Some pos);
                  raise (Exceptions.Skip_pointer_dereference (desc, try assert false with Assert_failure x -> x))
              | Prover_checks _ | Cannot_combine | Missing_sigma_not_empty | Missing_fld_not_empty ->
                  trace_call Specs.CallStats.CR_not_met;
                  assert false
            else (* no dereference error detected *)
              let desc =
                if IList.exists (function Cannot_combine -> true | _ -> false) invalid_res then
                  call_desc (Some Localise.Pnm_dangling)
                else if IList.exists (function
                    | Prover_checks (check :: _) ->
                        trace_call Specs.CallStats.CR_not_met;
                        let exn = get_check_exn check callee_pname loc (try assert false with Assert_failure x -> x) in
                        raise exn
                    | _ -> false) invalid_res then
                  call_desc (Some Localise.Pnm_bounds)
                else call_desc None in
              trace_call Specs.CallStats.CR_not_met;
              raise (Exceptions.Precondition_not_met (desc, try assert false with Assert_failure x -> x))
          end
        else (* combine the valid results, and store diverging states *)
          let process_valid_res vr =
            let save_diverging_states () =
              if not vr.incons_pre_missing && vr.vr_cons_res = [] then (* no consistent results on one spec: divergence *)
                let incons_res = IList.map (fun (p, path) -> (prop_pure_to_footprint p, path)) vr.vr_incons_res in
                State.add_diverging_states (Paths.PathSet.from_renamed_list incons_res) in
            save_diverging_states ();
            vr.vr_cons_res in
          IList.map (fun (p, path) -> (prop_pure_to_footprint p, path)) (IList.flatten (IList.map process_valid_res valid_res))
      end
    else if valid_res_no_miss_pi != [] then
      IList.flatten (IList.map (fun vr -> vr.vr_cons_res) valid_res_no_miss_pi)
    else if valid_res_miss_pi == [] then
      raise (Exceptions.Precondition_not_met (call_desc None, try assert false with Assert_failure x -> x))
    else
      begin
        L.d_strln "Missing pure facts for the function call:";
        IList.iter print_pi (IList.map (fun vr -> vr.vr_pi) valid_res_miss_pi);
        match Prover.find_minimum_pure_cover (IList.map (fun vr -> (vr.vr_pi, vr.vr_cons_res)) valid_res_miss_pi) with
        | None ->
            trace_call Specs.CallStats.CR_not_met;
            raise (Exceptions.Precondition_not_met (call_desc None, try assert false with Assert_failure x -> x))
        | Some cover ->
            L.d_strln "Found minimum cover";
            IList.iter print_pi (IList.map fst cover);
            IList.flatten (IList.map snd cover)
      end in
  trace_call Specs.CallStats.CR_success;
  let res =
    IList.map
      (fun (p, path) -> (quantify_path_idents_remove_constant_strings p, path))
      res_with_path_idents in
  let should_add_ret_attr _ =
    let is_likely_getter pn = IList.length (Procname.java_get_parameters pn) = 0 in
    !Config.idempotent_getters &&
    !Config.curr_language = Config.Java &&
    is_likely_getter callee_pname in
  match ret_ids with
  | [ret_id] when should_add_ret_attr ()->
      (* add attribute to remember what function call a return id came from *)
      let ret_var = Sil.Var ret_id in
      let mark_id_as_retval (p, path) =
        let att_retval = Sil.Aretval callee_pname in
        Prop.set_exp_attribute p ret_var att_retval, path in
      IList.map mark_id_as_retval res
  | _ -> res

(** Execute the function call and return the list of results with return value *)
let exe_function_call tenv cfg ret_ids caller_pdesc callee_pname loc actual_params prop path =
  let caller_pname = Cfg.Procdesc.get_proc_name caller_pdesc in
  let trace_call res =
    match Specs.get_summary caller_pname with
    | None -> ()
    | Some summary ->
        Specs.CallStats.trace
          summary.Specs.stats.Specs.call_stats callee_pname loc res !Config.footprint in
  let spec_list, formal_params = spec_find_rename trace_call callee_pname in
  let nspecs = IList.length spec_list in
  L.d_strln ("Found " ^ string_of_int nspecs ^ " specs for function " ^ Procname.to_string callee_pname);
  L.d_strln ("START EXECUTING SPECS FOR " ^ Procname.to_string callee_pname ^ " from state");
  Prop.d_prop prop; L.d_ln ();
  let exe_one_spec (n, spec) = exe_spec tenv cfg ret_ids (n, nspecs) caller_pdesc callee_pname loc prop path spec actual_params formal_params in
  let results = IList.map exe_one_spec spec_list in
  exe_call_postprocess tenv ret_ids trace_call callee_pname loc prop results