(* *********************************************************************)
(*                                                                     *)
(*              The Compcert verified compiler                         *)
(*                                                                     *)
(*          Xavier Leroy, INRIA Paris-Rocquencourt                     *)
(*                                                                     *)
(*  Copyright Institut National de Recherche en Informatique et en     *)
(*  Automatique.  All rights reserved.  This file is distributed       *)
(*  under the terms of the GNU General Public License as published by  *)
(*  the Free Software Foundation, either version 2 of the License, or  *)
(*  (at your option) any later version.  This file is also distributed *)
(*  under the terms of the INRIA Non-Commercial License Agreement.     *)
(*                                                                     *)
(* *********************************************************************)
(* and a few modifications... *)
(** Arithmetic and logical operators for the Compcert C and Clight languages *)
(*In this file, only Clight-independent (but possibly Ctypes-dependent) notions are defined. Maybe rename file to CommonOp.v ?*)
(** Computational version of type_eq **)
Definition eqb_option {A} (f: A -> A -> bool) (x y: option A) : bool :=
match x, y with
| None, None => true
| Some x' , Some y' => f x' y'
| _, _ => false
end.
Definition eqb_attr (a b: attr) : bool :=
match a, b with
| mk_attr av an, mk_attr bv bn => eqb av bv && eqb_option N.eqb an bn
end.
Definition eqb_floatsize (a b: floatsize) : bool :=
match a , b with
| F32, F32 => true
| F64, F64 => true
| _, _ => false
end.
Definition eqb_ident : ident -> ident -> bool := Pos.eqb.
Definition eqb_intsize (a b: intsize) : bool :=
match a , b with
| I8, I8 => true
| I16, I16 => true
| I32, I32 => true
| IBool, IBool => true
| _, _ => false
end.
Definition eqb_signedness (a b : signedness) :=
match a, b with
| Signed, Signed => true
| Unsigned, Unsigned => true
| _, _ => false
end.
Definition eqb_calling_convention (a b: calling_convention) :=
andb (eqb (cc_vararg a) (cc_vararg b))
(andb  (eqb (cc_unproto a) (cc_unproto b))
(eqb (cc_structret a) (cc_structret b))).
Fixpoint eqb_type (a b: type) {struct a} : bool :=
match a, b with
| Tvoid, Tvoid => true
| Tint ia sa aa, Tint ib sb ab => andb (eqb_intsize ia ib)
(andb (eqb_signedness sa sb) (eqb_attr aa ab))
| Tlong sa aa, Tlong sb ab => andb (eqb_signedness sa sb) (eqb_attr aa ab)
| Tfloat sa aa, Tfloat sb ab => andb (eqb_floatsize sa sb) (eqb_attr aa ab)
| Tpointer ta aa, Tpointer tb ab => andb (eqb_type ta tb) (eqb_attr aa ab)
| Tarray ta sa aa, Tarray tb sb ab => andb (eqb_type ta tb)
(andb (Zeq_bool sa sb) (eqb_attr aa ab))
| Tfunction sa ta ca, Tfunction sb tb cb =>
andb (andb (eqb_typelist sa sb) (eqb_type ta tb)) (eqb_calling_convention ca cb)
| Tstruct ia aa, Tstruct ib ab => andb (eqb_ident ia ib) (eqb_attr aa ab)
| Tunion ia aa, Tunion ib ab => andb (eqb_ident ia ib) (eqb_attr aa ab)
| _, _ => false
end
with eqb_typelist (a b: typelist)  {struct a}: bool :=
match a, b with
| Tcons ta ra, Tcons tb rb => andb (eqb_type ta tb) (eqb_typelist ra rb)
| Tnil, Tnil => true
| _ , _ => false
end.
Scheme eqb_type_sch := Induction for type Sort Prop
with eqb_typelist_sch := Induction for  typelist Sort Prop.
Definition eqb_member (it1 it2: ident * type): bool :=
eqb_ident (fst it1) (fst it2) && eqb_type (snd it1) (snd it2).
Definition eqb_su (su1 su2: struct_or_union): bool :=
match su1, su2 with
| Struct, Struct
| Union, Union => true
| _, _ => false
end.
Definition log2_sizeof_pointer : N :=
ltac:(let n := eval compute in
(N.log2 (Z.to_N (@sizeof (PTree.empty _) (Tpointer Tvoid noattr))))
in exact (n)).
Definition int_or_ptr_type : type :=
Tpointer Tvoid {| attr_volatile := false; attr_alignas := Some log2_sizeof_pointer |}.
(** The following describes types that can be interpreted as a boolean: integers, floats, pointers.  It is used for the semantics of the [!] and [?] operators, as well as the [if], [while], [for] statements. *)
(** Interpretation of values as truth values. Non-zero integers, non-zero floats and non-null pointers are considered as true.  The integer zero (which also represents the null pointer) and the float 0.0 are false. *)
Definition bool_val_i (v : val) : option bool :=
match v with
| Vint n => Some (negb (Int.eq n Int.zero))
| _ => None
end.
Definition bool_val_p (v : val) : option bool :=
match v with
| Vint n => if Archi.ptr64 then None else Some (negb (Int.eq n Int.zero))
| Vlong n => if Archi.ptr64 then Some (negb (Int64.eq n Int64.zero)) else None
| Vptr b ofs => Some true
| _ => None
end.
Definition bool_val_s (v : val) : option bool :=
match v with
| Vsingle f => Some (negb (Float32.cmp Ceq f Float32.zero))
| _ => None
end.
Definition bool_val_f (v : val) : option bool :=
match v with
| Vfloat f => Some (negb (Float.cmp Ceq f Float.zero))
| _ => None
end.
Definition bool_val_l (v : val) : option bool :=
match v with
| Vlong n => Some (negb (Int64.eq n Int64.zero))
| Vptr b ofs =>
if negb Archi.ptr64 then None else Some true
| _ => None
end.
Definition bool_val (t: type) : val -> option bool :=
match t with
| Tint _ _ _ => bool_val_i
| Tpointer _ _ => if  eqb_type t int_or_ptr_type then (fun _ => None) else bool_val_p
| Tfloat F64 _ => bool_val_f
| Tfloat F32 _ => bool_val_s
| Tlong _ _ => bool_val_l
| _ => fun v => None
end.
(*************** from veric.expr.v   **********************)
Definition size_t := if Archi.ptr64 then Tlong Unsigned noattr else Tint I32 Unsigned noattr.
Definition is_int (sz: intsize) (sg: signedness) (v: val) :=
match v with
| Vint i =>
match sz, sg with
| I8, Signed => Byte.min_signed <= Int.signed i <= Byte.max_signed
| I8, Unsigned => Int.unsigned i <= Byte.max_unsigned
| I16, Signed => -two_p (16-1) <= Int.signed i <= two_p (16-1) -1
| I16, Unsigned => Int.unsigned i <= two_p 16 - 1
| I32, _ => True
| IBool, _ => i = Int.zero \/ i = Int.one
end
| _ => False
end.
Definition tc_val (ty: type) : val -> Prop :=
match ty with
| Tint sz sg _ => is_int sz sg
| Tlong _ _ => is_long
| Tfloat F64 _ => is_float
| Tfloat F32 _ => is_single
| Tpointer _ _ => if eqb_type ty int_or_ptr_type then is_pointer_or_integer else is_pointer_or_null
| Tarray _ _ _ | Tfunction _ _ _ => is_pointer_or_null
| Tstruct _ _ => isptr
| Tunion _ _ => isptr
| _ => fun _ => False
end.
Definition tc_val' t v := v <> Vundef -> tc_val t v.
Fixpoint tc_vals (ty: list type) (v: list val) : Prop :=
match v, ty with
| v1::vs , t1::ts => tc_val t1 v1 /\ tc_vals ts vs
| nil, nil => True
| _, _ => False
end.

Lemma tc_val_Vundef:
forall t, ~tc_val t Vundef.