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open Identifiers
open Types
module VarId = IdGen ()
module BorrowId = IdGen ()
module SymbolicValueId = IdGen ()
module AbstractionId = IdGen ()
module RegionId = IdGen ()
type var = {
index : VarId.id; (** Unique variable identifier *)
name : string option;
ty : ety;
(** The variable type - erased type, because variables are not used
** in function signatures *)
}
(** A variable *)
type big_int = Z.t
let big_int_of_yojson (json : Yojson.Safe.t) : (big_int, string) result =
match json with
| `Int i -> Ok (Z.of_int i)
| `Intlit is -> Ok (Z.of_string is)
| _ -> Error "not an integer or an integer literal"
let big_int_to_yojson (i : big_int) = `Intlit (Z.to_string i)
type scalar_value = { value : big_int; int_ty : integer_type }
(** A scalar value
Note that we use unbounded integers everywhere.
We then harcode the boundaries for the different types.
*)
(** A constant value *)
type constant_value =
| Scalar of scalar_value
| Bool of bool
| Char of char
| String of string
type symbolic_value = { sv_id : SymbolicValueId.id; sv_ty : rty }
(** Symbolic value *)
type symbolic_proj_comp = {
svalue : symbolic_value; (** The symbolic value itself *)
rset_ended : RegionId.Set.t;
(** The regions used in the symbolic value which have already ended *)
}
(** A complementary projector over a symbolic value.
"Complementary" stands for the fact that it is a projector over all the
regions *but* the ones which are listed in the projector.
*)
(** An untyped value, used in the environments *)
type value =
| Concrete of constant_value (** Concrete (non-symbolic) value *)
| Adt of adt_value (** Enumerations and structures *)
| Tuple of typed_value FieldId.vector
(** Tuple - note that units are encoded as 0-tuples *)
| Bottom (** No value (uninitialized or moved value) *)
| Assumed of assumed_value (** Assumed types (Box, Vec, Cell...) *)
| Borrow of borrow_content (** A borrowed value *)
| Loan of loan_content (** A loaned value *)
| Symbolic of symbolic_proj_comp (** Unknown value *)
and adt_value = {
def_id : TypeDefId.id;
variant_id : VariantId.id option;
regions : erased_region list;
types : ety list;
field_values : typed_value FieldId.vector;
}
and borrow_content =
| SharedBorrow of BorrowId.id (** A shared value *)
| MutBorrow of BorrowId.id * typed_value (** A mutably borrowed value *)
| InactivatedMutBorrow of BorrowId.id
(** An inactivated mut borrow.
This is used to model two-phase borrows. When evaluating a two-phase
mutable borrow, we first introduce an inactivated borrow which behaves
like a shared borrow, until the moment we actually *use* the borrow:
at this point, we end all the other shared borrows (or inactivated borrows
- though there shouldn't be any other inactivated borrows if the program
is well typed) of this value and replace the inactivated borrow with a
mutable borrow.
*)
and loan_content =
| SharedLoan of BorrowId.Set.t * typed_value
| MutLoan of BorrowId.id
and assumed_value = Box of typed_value
and typed_value = { value : value; ty : ety }
type abstract_shared_borrows =
| AsbSet of BorrowId.Set.t
| AsbProjReborrows of symbolic_value * rty
| AsbUnion of abstract_shared_borrows * abstract_shared_borrows
(** TODO: explanations *)
(** Abstraction values are used inside of abstractions to properly model
borrowing relations introduced by function calls.
When calling a function, we lose information about the borrow graph:
part of it is thus "abstracted" away.
*)
type avalue =
| AConcrete of constant_value
| AAdt of aadt_value
| ATuple of typed_avalue FieldId.vector
| ABottom
| ALoan of aloan_content
| ABorrow of aborrow_content
| AAssumed of aassumed_value
| AProj of aproj
and aadt_value = {
adef_id : TypeDefId.id;
avariant_id : VariantId.id option;
aregions : erased_region list;
atypes : rty list;
afield_values : typed_avalue FieldId.vector;
}
and aloan_content =
| AMutLoan of BorrowId.id * typed_avalue
| ASharedLoan of BorrowId.Set.t * typed_value * typed_avalue
| AEndedMutLoan of { given_back : typed_value; child : typed_avalue }
| AEndedSharedLoan of typed_value * typed_avalue
| AIgnoredMutLoan of BorrowId.id * typed_avalue
| AIgnoredSharedLoan of abstract_shared_borrows
(** Note that when a borrow content is ended, it is replaced by Bottom (while
we need to track ended loans more precisely, especially because of their
children values) *)
and aborrow_content =
| AMutBorrow of BorrowId.id * typed_avalue
| ASharedBorrow of BorrowId.id
| AIgnoredMutBorrow of typed_avalue
| AEndedIgnoredMutLoan of { given_back : typed_avalue; child : typed_avalue }
| AIgnoredSharedBorrow of abstract_shared_borrows
and aassumed_value = ABox of typed_avalue
and aproj =
| AProjLoans of symbolic_value
| AProjBorrows of symbolic_value * rty
and typed_avalue = { avalue : avalue; aty : rty }
type abs = {
abs_id : AbstractionId.id;
parents : AbstractionId.Set.t; (** The parent abstractions *)
acc_regions : RegionId.Set.t;
(** Union of the regions owned by the (transitive) parent abstractions and
by the current abstraction *)
regions : RegionId.Set.t; (** Regions owned by this abstraction *)
avalues : typed_avalue list; (** The values in this abstraction *)
}
(** Abstractions model the parts in the borrow graph where the borrowing relations
have been abstracted because of a function call.
In order to model the relations between the borrows, we use "abstraction values",
which are a special kind of value.
*)
|
