(** We model the following registers of the RISC-V architecture. *)

Inductive preg: Type :=
  | IR: ireg -> preg                    (**r integer registers *)
  | FR: freg -> preg                    (**r double-precision float registers *)
  | PC: preg.(** We model the following registers of the RISC-V architecture. *)

Inductive preg: Type :=
  | IR: ireg -> preg                    (**r integer registers *)
  | FR: freg -> preg                    (**r double-precision float registers *)
  | PC: preg.(** We model the following registers of the RISC-V architecture. *)

Inductive preg: Type :=
  | IR: ireg -> preg                    (**r integer registers *)
  | FR: freg -> preg                    (**r double-precision float registers *)
  | PC: preg.(** We model the following registers of the RISC-V architecture. *)

Inductive preg: Type :=
  | IR: ireg -> preg                    (**r integer registers *)
  | FR: freg -> preg                    (**r double-precision float registers *)
  | PC: preg.

Lemma preg_eq: forall (x y: preg), {x=y} + {x<>y}.