bedrock.lang.cpp.logic.path_pred

(*
* Copyright (c) 2020-2024 BedRock Systems, Inc.
* This software is distributed under the terms of the BedRock Open-Source License.
* See the LICENSE-BedRock file in the repository root for details.
*)
Require Import bedrock.prelude.base.

Require Import bedrock.lang.proofmode.proofmode.
Require Import bedrock.lang.cpp.semantics.
Require Import bedrock.lang.cpp.logic.pred.
Require Import bedrock.lang.cpp.syntax.

#[deprecated(since="20231103",note="use [ptr].")]
Notation Loc := ptr (only parsing).

Section with_Σ.
Context `{has_cpp : cpp_logic}.

absolute locations _eqv v represents the pointer of a val. The resulting pointer is invalid if v is not a ptr.

NOTE this does *not* do things like converting integers to pointers.

  Definition _eqv (a : val) : ptr :=
    match a with
    | Vptr p => p
    | _ => invalid_ptr
    end.

  Lemma _eqv_eq : forall p , _eqv (Vptr p) = p.
  Proof. reflexivity. Qed.

  Definition _global_def (resolve : genv) (x : obj_name) : ptr :=
    global_ptr resolve.(genv_tu) x.
  Definition _global_aux : seal (@_global_def). Proof. by eexists. Qed.
  Definition _global := _global_aux.(unseal).
  Definition _global_eq : @_global = _ := _global_aux.(seal_eq).

  #[global] Instance _global_inj {resolve : genv} : Inj (=) (=) (_global resolve).
  Proof. rewrite _global_eq. apply _. Qed.

  Lemma _global_nonnull resolve n : _global resolve n <> nullptr.
  Proof. rewrite _global_eq /_global_def. apply global_ptr_nonnull. Qed.
End with_Σ.

Arguments _global {resolve} _ : rename.

(* this is for `Indirect` field references *)
Fixpoint path_to_Offset {σ:genv} (from : globname) (final : field_name.t lang.cpp)
         (ls : list (field_name.t lang.cpp * globname))
  : offset :=
  match ls with
  | [] => o_field σ (Field from final)
  | (i, c) :: ls =>
    o_field σ (Field from i) ,, path_to_Offset c final ls
  end.

offset_for cls f returns the offset of f where the base is this and has type Tnamed cls.

NOTE this function assumes that f is well-typed.

Definition offset_for {σ:genv} (cls : globname) (f : InitPath) : offset :=
  match f with
  | InitBase parent => o_base σ cls parent
  | InitField i => o_field σ $ Field cls i
  | InitIndirect ls final => path_to_Offset cls final ls
  | InitThis => o_id
  end.