path: root/src/Interpreter.ml

module L = Logging
module T = Types
module A = CfimAst
module M = Modules
open Cps
open InterpreterUtils
open InterpreterStatements

(* TODO: it would be good to find a "core", which implements the rules (like
   "end_borrow") and on top of which we build more complex functions which
   chose in which order to apply the rules, etc. This way we would make very
   explicit where we need to insert sanity checks, what the preconditions are,
   where invariants might be broken, etc.
*)

(* TODO: intensively test with PLT-redex *)

(* TODO: remove the config parameters when they are useless *)

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

module Test = struct
  let initialize_context (m : M.cfim_module) (type_vars : T.type_var list) :
      C.eval_ctx =
    let type_decls, _ = M.split_declarations m.declarations in
    let type_defs, fun_defs = M.compute_defs_maps m in
    let type_defs_groups, _funs_defs_groups =
      M.split_declarations_to_group_maps m.declarations
    in
    let type_infos =
      TypesAnalysis.analyze_type_declarations type_defs type_decls
    in
    let type_context = { C.type_defs_groups; type_defs; type_infos } in
    C.reset_global_counters ();
    {
      C.type_context;
      C.fun_context = fun_defs;
      C.type_vars;
      C.env = [];
      C.ended_regions = T.RegionId.Set.empty;
    }

  (** Initialize an evaluation context to execute a function.

      Introduces local variables initialized in the following manner:
      - input arguments are initialized as symbolic values
      - the remaining locals are initialized as ⊥
      "Dummy" abstractions are introduced for the regions present in the
      function signature.
   *)
  let initialize_symbolic_context_for_fun (m : M.cfim_module) (fdef : A.fun_def)
      : C.eval_ctx =
    (* The abstractions are not initialized the same way as for function
     * calls: they contain *loan* projectors, because they "provide" us
     * with the input values (which behave as if they had been returned
     * by some function calls...).
     * Also, note that we properly set the set of parents of every abstraction:
     * this should not be necessary, as those abstractions should never be
     * *automatically* ended (because ending some borrows requires to end
     * one of them), but rather selectively ended when generating code
     * for each of the backward functions. We do it only because we can
     * do it, and because it gives a bit of sanity.
     * *)
    let sg = fdef.signature in
    (* Create the context *)
    let ctx = initialize_context m sg.type_params in
    (* Instantiate the signature *)
    let type_params =
      List.map (fun tv -> T.TypeVar tv.T.index) sg.type_params
    in
    let ctx, inst_sg = instantiate_fun_sig type_params sg ctx in
    (* Create fresh symbolic values for the inputs *)
    let input_svs =
      List.map
        (fun ty -> mk_fresh_symbolic_value V.SynthInput ty)
        inst_sg.inputs
    in
    (* Initialize the abstractions as empty (i.e., with no avalues) abstractions *)
    let call_id = C.fresh_fun_call_id () in
    assert (call_id = V.FunCallId.zero);
    let empty_absl =
      create_empty_abstractions_from_abs_region_groups call_id V.Synth
        inst_sg.A.regions_hierarchy
    in
    (* Add the avalues to the abstractions and insert them in the context *)
    let insert_abs (ctx : C.eval_ctx) (abs : V.abs) : C.eval_ctx =
      (* Project over the values - we use *loan* projectors, as explained above *)
      let avalues =
        List.map
          (mk_aproj_loans_value_from_symbolic_value abs.regions)
          input_svs
      in
      (* Insert the avalues in 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
    let ctx = List.fold_left insert_abs ctx empty_absl in
    (* Split the variables between return var, inputs and remaining locals *)
    let ret_var = List.hd fdef.locals in
    let input_vars, local_vars =
      Collections.List.split_at (List.tl fdef.locals) fdef.arg_count
    in
    (* Push the return variable (initialized with ⊥) *)
    let ctx = C.ctx_push_uninitialized_var ctx ret_var in
    (* Push the input variables (initialized with symbolic values) *)
    let input_values = List.map mk_typed_value_from_symbolic_value input_svs in
    let ctx = C.ctx_push_vars ctx (List.combine input_vars input_values) in
    (* Push the remaining local variables (initialized with ⊥) *)
    let ctx = C.ctx_push_uninitialized_vars ctx local_vars in
    (* Return *)
    ctx

  (** Test a unit function (taking no arguments) by evaluating it in an empty
      environment.
   *)
  let test_unit_function (config : C.partial_config) (m : M.cfim_module)
      (fid : A.FunDefId.id) : unit =
    (* Retrieve the function declaration *)
    let fdef = A.FunDefId.nth m.functions fid in

    (* Debug *)
    log#ldebug
      (lazy ("test_unit_function: " ^ Print.name_to_string fdef.A.name));

    (* Sanity check - *)
    assert (List.length fdef.A.signature.region_params = 0);
    assert (List.length fdef.A.signature.type_params = 0);
    assert (fdef.A.arg_count = 0);

    (* Create the evaluation context *)
    let ctx = initialize_context m [] in

    (* Insert the (uninitialized) local variables *)
    let ctx = C.ctx_push_uninitialized_vars ctx fdef.A.locals in

    (* Create the continuation to check the function's result *)
    let cf_check res _ =
      match res with
      | Return -> (* Ok *) None
      | _ ->
          failwith
            ("Unit test failed (concrete execution) on: "
            ^ Print.name_to_string fdef.A.name)
    in

    (* Evaluate the function *)
    let config = C.config_of_partial C.ConcreteMode config in
    let _ = eval_function_body config fdef.A.body cf_check ctx in
    ()

  (** Small helper: return true if the function is a unit function (no parameters,
    no arguments) - TODO: move *)
  let fun_def_is_unit (def : A.fun_def) : bool =
    def.A.arg_count = 0
    && List.length def.A.signature.region_params = 0
    && List.length def.A.signature.type_params = 0
    && List.length def.A.signature.inputs = 0

  (** Test all the unit functions in a list of function definitions *)
  let test_unit_functions (config : C.partial_config) (m : M.cfim_module) : unit
      =
    let unit_funs = List.filter fun_def_is_unit m.functions in
    let test_unit_fun (def : A.fun_def) : unit =
      test_unit_function config m def.A.def_id
    in
    List.iter test_unit_fun unit_funs

  (** Execute the symbolic interpreter on a function. *)
  let test_function_symbolic (config : C.partial_config) (m : M.cfim_module)
      (fid : A.FunDefId.id) : unit =
    (* Retrieve the function declaration *)
    let fdef = A.FunDefId.nth m.functions fid in

    (* Debug *)
    log#ldebug
      (lazy ("test_function_symbolic: " ^ Print.name_to_string fdef.A.name));

    (* Create the evaluation context *)
    let ctx = initialize_symbolic_context_for_fun m fdef in

    (* Create the continuation to check the function's result *)
    let cf_check res _ =
      match res with
      | Return | Panic ->
          (* Note that as we explore all the execution branches, one of
           * the executions can lead to a panic *)
          None
      | _ ->
          failwith
            ("Unit test failed (symbolic execution) on: "
            ^ Print.name_to_string fdef.A.name)
    in

    (* Evaluate the function *)
    let config = C.config_of_partial C.SymbolicMode config in
    let _ = eval_function_body config fdef.A.body cf_check ctx in
    ()

  (** Execute the symbolic interpreter on a list of functions.

      TODO: for now we ignore the functions which contain loops, because
      they are not supported by the symbolic interpreter.
   *)
  let test_functions_symbolic (config : C.partial_config) (m : M.cfim_module) :
      unit =
    let no_loop_funs =
      List.filter (fun f -> not (CfimAstUtils.fun_def_has_loops f)) m.functions
    in
    let test_fun (def : A.fun_def) : unit =
      (* Execute the function - note that as the symbolic interpreter explores
       * all the path, some executions are expected to "panic": we thus don't
       * check the return value *)
      test_function_symbolic config m def.A.def_id
    in
    List.iter test_fun no_loop_funs
end