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(*
* Copyright (c) Facebook, Inc. and its affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*)
(** Terms
Pure (heap-independent) terms are arithmetic, bitwise-logical, etc.
operations over literal values and variables. *)
type op1 =
| Signed of {bits: int}
(** [Ap1 (Signed {bits= n}, arg)] is [arg] interpreted as an [n]-bit
signed integer. That is, it two's-complement--decodes the low [n]
bits of the infinite two's-complement encoding of [arg]. *)
| Unsigned of {bits: int}
(** [Ap1 (Unsigned {bits= n}, arg)] is [arg] interpreted as an
[n]-bit unsigned integer. That is, it unsigned-binary--decodes the
low [n] bits of the infinite two's-complement encoding of [arg]. *)
| Convert of {src: Typ.t; dst: Typ.t}
(** [Ap1 (Convert {src; dst}, arg)] is [arg] converted from type [src]
to type [dst], possibly with loss of information. The [src] and
[dst] types must be [Typ.convertible] and must not both be
[Integer] types. *)
| Splat (** Iterated concatenation of a single byte *)
| Select of int (** Select an index from a record *)
[@@deriving compare, equal, hash, sexp]
type op2 =
| Eq (** Equal test *)
| Dq (** Disequal test *)
| Lt (** Less-than test *)
| Le (** Less-than-or-equal test *)
| Ord (** Ordered test (neither arg is nan) *)
| Uno (** Unordered test (some arg is nan) *)
| Div (** Division, for integers result is truncated toward zero *)
| Rem
(** Remainder of division, satisfies [a = b * div a b + rem a b] and
for integers [rem a b] has same sign as [a], and [|rem a b| < |b|] *)
| Xor (** Exclusive-or, bitwise *)
| Shl (** Shift left, bitwise *)
| Lshr (** Logical shift right, bitwise *)
| Ashr (** Arithmetic shift right, bitwise *)
| Memory (** Size-tagged byte-array *)
| Update of int (** Constant record with updated index *)
[@@deriving compare, equal, hash, sexp]
type op3 =
| Conditional (** If-then-else *)
| Extract (** Extract a slice of an aggregate value *)
[@@deriving compare, equal, hash, sexp]
type opN =
| Concat (** Byte-array concatenation *)
| Record (** Record (array / struct) constant *)
[@@deriving compare, equal, hash, sexp]
type recN = Record (** Recursive record (array / struct) constant *)
[@@deriving compare, equal, hash, sexp]
module rec Set : sig
include Import.Set.S with type elt := T.t
val hash_fold_t : t Hash.folder
val t_of_sexp : Sexp.t -> t
end
and Qset : sig
include Import.Qset.S with type elt := T.t
val hash_fold_t : t Hash.folder
val t_of_sexp : Sexp.t -> t
end
and T : sig
type set = Set.t [@@deriving compare, equal, hash, sexp]
type qset = Qset.t [@@deriving compare, equal, hash, sexp]
and t = private
| Var of {id: int; name: string}
(** Local variable / virtual register *)
| Ap1 of op1 * t (** Unary application *)
| Ap2 of op2 * t * t (** Binary application *)
| Ap3 of op3 * t * t * t (** Ternary application *)
| ApN of opN * t iarray (** N-ary application *)
| RecN of recN * t iarray
(** Recursive n-ary application, may recursively refer to itself
(transitively) from its args. NOTE: represented by cyclic
values. *)
| And of set (** Conjunction, boolean or bitwise *)
| Or of set (** Disjunction, boolean or bitwise *)
| Add of qset (** Sum of terms with rational coefficients *)
| Mul of qset (** Product of terms with rational exponents *)
| Label of {parent: string; name: string}
(** Address of named code block within parent function *)
| Nondet of {msg: string}
(** Anonymous local variable with arbitrary value, representing
non-deterministic approximation of value described by [msg] *)
| Float of {data: string} (** Floating-point constant *)
| Integer of {data: Z.t} (** Integer constant *)
| Rational of {data: Q.t} (** Rational constant *)
[@@deriving compare, equal, hash, sexp]
end
include module type of T with type t = T.t
(** Term.Var is re-exported as Var *)
module Var : sig
type term := t
type t = private term [@@deriving compare, equal, hash, sexp]
type strength = t -> [`Universal | `Existential | `Anonymous] option
module Map : Map.S with type key := t
module Set : sig
include Import.Set.S with type elt := t
val hash_fold_t : t Hash.folder
val sexp_of_t : t -> Sexp.t
val t_of_sexp : Sexp.t -> t
val ppx : strength -> t pp
val pp : t pp
val pp_xs : t pp
end
val pp : t pp
include Invariant.S with type t := t
val name : t -> string
val id : t -> int
val is_global : t -> bool
val of_ : term -> t
val of_term : term -> t option
val program : ?global:unit -> string -> t
val fresh : string -> wrt:Set.t -> t * Set.t
val identified : name:string -> id:int -> t
(** Variable with the given [id]. Variables are compared by [id] alone,
[name] is used only for printing. The only way to ensure [identified]
variables do not clash with [fresh] variables is to pass the
[identified] variables to [fresh] in [wrt]:
[Var.fresh name ~wrt:(Var.Set.of_ (Var.identified ~name ~id))]. *)
module Subst : sig
type var := t
type t [@@deriving compare, equal, sexp]
val pp : t pp
val empty : t
val freshen : Set.t -> wrt:Set.t -> t
val invert : t -> t
val restrict : t -> Set.t -> t
val is_empty : t -> bool
val domain : t -> Set.t
val range : t -> Set.t
val apply_set : t -> Set.t -> Set.t
val fold : t -> init:'a -> f:(var -> var -> 'a -> 'a) -> 'a
end
end
module Map : sig
include Map.S with type key := t
val t_of_sexp : (Sexp.t -> 'a) -> Sexp.t -> 'a t
end
val ppx : Var.strength -> t pp
val pp : t pp
val pp_diff : (t * t) pp
val invariant : t -> unit
(** Construct *)
(* variables *)
val var : Var.t -> t
(* constants *)
val nondet : string -> t
val label : parent:string -> name:string -> t
val null : t
val bool : bool -> t
val true_ : t
val false_ : t
val integer : Z.t -> t
val zero : t
val one : t
val minus_one : t
val rational : Q.t -> t
val float : string -> t
(* type conversions *)
val signed : int -> t -> t
val unsigned : int -> t -> t
val convert : Typ.t -> to_:Typ.t -> t -> t
(* comparisons *)
val eq : t -> t -> t
val dq : t -> t -> t
val lt : t -> t -> t
val le : t -> t -> t
val ord : t -> t -> t
val uno : t -> t -> t
(* arithmetic *)
val neg : t -> t
val add : t -> t -> t
val sub : t -> t -> t
val mul : t -> t -> t
val div : t -> t -> t
val rem : t -> t -> t
(* boolean / bitwise *)
val and_ : t -> t -> t
val or_ : t -> t -> t
val not_ : t -> t
(* bitwise *)
val xor : t -> t -> t
val shl : t -> t -> t
val lshr : t -> t -> t
val ashr : t -> t -> t
(* if-then-else *)
val conditional : cnd:t -> thn:t -> els:t -> t
(* aggregate sizes *)
val agg_size_exn : t -> t
val agg_size : t -> t option
(* aggregates (memory contents) *)
val splat : t -> t
val memory : siz:t -> arr:t -> t
val extract : agg:t -> off:t -> len:t -> t
val concat : t array -> t
val eq_concat : t * t -> (t * t) array -> t
(* records (struct / array values) *)
val record : t iarray -> t
val select : rcd:t -> idx:int -> t
val update : rcd:t -> idx:int -> elt:t -> t
(* recursive n-ary application *)
val rec_app :
(module Hashtbl.Key_plain with type t = 'id)
-> (id:'id -> recN -> t lazy_t iarray -> t) Staged.t
val size_of : Typ.t -> t
(** Transform *)
val map : t -> f:(t -> t) -> t
val map_rec_pre : t -> f:(t -> t option) -> t
(** Pre-order transformation that preserves cycles. Each subterm [x] from
root to leaves is presented to [f]. If [f x = Some x'] then the subterms
of [x] are not traversed and [x] is transformed to [x']. Otherwise
traversal proceeds to the subterms of [x], followed by rebuilding the
term structure on the transformed subterms. Cycles (through terms
involving [RecN]) are preserved. *)
val fold_map : t -> init:'a -> f:('a -> t -> 'a * t) -> 'a * t
val fold_map_rec_pre :
t -> init:'a -> f:('a -> t -> ('a * t) option) -> 'a * t
val rename : Var.Subst.t -> t -> t
(** Traverse *)
val iter : t -> f:(t -> unit) -> unit
val exists : t -> f:(t -> bool) -> bool
val fold : t -> init:'a -> f:(t -> 'a -> 'a) -> 'a
val fold_vars : t -> init:'a -> f:('a -> Var.t -> 'a) -> 'a
val fold_terms : t -> init:'a -> f:('a -> t -> 'a) -> 'a
(** Query *)
val fv : t -> Var.Set.t
val is_true : t -> bool
val is_false : t -> bool
val is_constant : t -> bool
(** Test if a term's semantics is independent of the values of variables. *)
val height : t -> int
(** Solve *)
val solve_zero_eq : ?for_:t -> t -> (t * t) option
(** [solve_zero_eq d] is [Some (e, f)] if [d = 0] can be equivalently
expressed as [e = f] for some monomial subterm [e] of [d]. If [for_] is
passed, then the subterm [e] must be [for_]. *)