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63 lines
1.8 KiB
63 lines
1.8 KiB
(*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*)
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open! IStd
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(** Environment for temporary identifiers used in instructions. Lazy implementation: only created
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when actually used. *)
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type t = Exp.t Ident.Hash.t Lazy.t
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let create_ proc_desc =
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let map = Ident.Hash.create 1 in
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let do_instr _ = function
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| Sil.Load {id; e} ->
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Ident.Hash.add map id e
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| Sil.Call ((res_ident, _), Exp.Const (Const.Cfun fname), [(Exp.Var src_ident, _); _], _, _)
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(* [id] = __cast([ex]) when [ex] is a frontend temporary, try to unfold it further *)
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when Procname.equal fname BuiltinDecl.__cast ->
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Ident.Hash.find_opt map src_ident
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|> Option.iter ~f:(fun ex -> Ident.Hash.add map res_ident ex)
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| _ ->
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()
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in
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Procdesc.iter_instrs do_instr proc_desc ;
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map
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(* lazy implementation, only create when used *)
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let create proc_desc =
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let map = lazy (create_ proc_desc) in
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map
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let lookup map_ id =
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let map = Lazy.force map_ in
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Ident.Hash.find_opt map id
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let expand_expr idenv e =
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match e with Exp.Var id -> ( match lookup idenv id with Some e' -> e' | None -> e ) | _ -> e
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let expand_expr_temps idenv node exp_ =
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let exp = expand_expr idenv exp_ in
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match exp with
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| Exp.Lvar pvar when Pvar.is_frontend_tmp pvar -> (
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match Decompile.find_program_variable_assignment node pvar with
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| None ->
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exp
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| Some (_, id) ->
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expand_expr idenv (Exp.Var id) )
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| _ ->
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exp
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(** Return true if the expression is a temporary variable introduced by the front-end. *)
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let exp_is_temp idenv e =
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match expand_expr idenv e with Exp.Lvar pvar -> Pvar.is_frontend_tmp pvar | _ -> false
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