Definition const_only_isUnOpResultType {CS: compspecs} op (typeof_a:type) valueof_a ty : bool :=
match op with
| Cop.Onotbool => match typeof_a with
| Tint _ _ _
| Tlong _ _
| Tfloat _ _ => is_int_type ty
| Tpointer _ _ =>
if Archi.ptr64
then match valueof_a with
| Vlong v =>
andb (negb (eqb_type (typeof_a) int_or_ptr_type))
(andb (is_int_type ty) (Z.eqb 0 (Int64.unsigned v)))
| _ => false
end
else match valueof_a with
| Vint v =>
andb (negb (eqb_type typeof_a int_or_ptr_type))
(andb (is_int_type ty) (Z.eqb 0 (Int.unsigned v)))
| _ => false
end
| _ => false
end
| Cop.Onotint => match Cop.classify_notint (typeof_a) with
| Cop.notint_default => false
| Cop.notint_case_i _ => (is_int32_type ty)
| Cop.notint_case_l _ => (is_long_type ty)
end
| Cop.Oneg => match Cop.classify_neg (typeof_a) with
| Cop.neg_case_i sg =>
andb (is_int32_type ty)
match (typeof_a) with
| Tint _ Signed _ =>
match valueof_a with
| Vint v => negb (Z.eqb (Int.signed v) Int.min_signed)
| _ => false
end
| Tlong Signed _ =>
match valueof_a with
| Vlong v => negb (Z.eqb (Int64.signed v) Int64.min_signed)
| _ => false
end
| _ => true
end
| Cop.neg_case_f => is_float_type ty
| Cop.neg_case_s => is_single_type ty
| _ => false
end
| Cop.Oabsfloat =>match Cop.classify_neg (typeof_a) with
| Cop.neg_case_i sg => is_float_type ty
| Cop.neg_case_l _ => is_float_type ty
| Cop.neg_case_f => is_float_type ty
| Cop.neg_case_s => is_float_type ty
| _ => false
end
end.
(* TODO: binarithType would better be bool type *)
Definition const_only_isBinOpResultType {CS: compspecs} op typeof_a1 valueof_a1 typeof_a2 valueof_a2 ty : bool :=
match op with
| Cop.Oadd =>
match Cop.classify_add (typeof_a1) (typeof_a2) with
| Cop.add_case_pi t _ | Cop.add_case_pl t =>
andb
(andb
(andb (match valueof_a1 with Vptr _ _ => true | _ => false end) (complete_type cenv_cs t))
(negb (eqb_type (typeof_a1) int_or_ptr_type)))
(is_pointer_type ty)
| Cop.add_case_ip _ t | Cop.add_case_lp t =>
andb
(andb
(andb (match valueof_a2 with Vptr _ _ => true | _ => false end) (complete_type cenv_cs t))
(negb (eqb_type (typeof_a2) int_or_ptr_type)))
(is_pointer_type ty)
| Cop.add_default => false
(* andb (binarithType (typeof a1) (typeof a2) ty deferr reterr) (tc_nobinover Z.add a1 a2) *)
end
| _ => false (* TODO *)
end.
Definition const_only_isCastResultType {CS: compspecs} (t1 t2: type) (valueof_a: val)  : bool := false. (* TODO *)
Fixpoint const_only_eval_expr {cs: compspecs} (e: Clight.expr): option val :=
match e with
| Econst_int i (Tint I32 _ _) => Some (Vint i)
| Econst_int _ _ => None
| Econst_long i ty => None (*Some (Vlong i) *)
| Econst_float f (Tfloat F64 _) => Some (Vfloat f)
| Econst_float _ _ => None
| Econst_single f (Tfloat F32 _) => Some (Vsingle f)
| Econst_single _ _ => None
| Etempvar id ty => None
| Evar _ _ => None
| Eaddrof a ty => None
| Eunop op a ty =>
match const_only_eval_expr a with
| Some v => if const_only_isUnOpResultType op (typeof a) v ty
then Some (eval_unop op (typeof a) v)
else None
| None => None
end
| Ebinop op a1 a2 ty =>
match (const_only_eval_expr a1), (const_only_eval_expr a2) with
| Some v1, Some v2 =>
if const_only_isBinOpResultType op (typeof a1) v1 (typeof a2) v2 ty
then Some (eval_binop op (typeof a1) (typeof a2) v1 v2)
else None
| _, _ => None
end
| Ecast a ty =>
match const_only_eval_expr a with
| Some v => if const_only_isCastResultType (typeof a) ty v
then Some (eval_cast (typeof a) ty v)
else None
| None => None
end
| Ederef a ty => None
| Efield a i ty => None
| Esizeof t t0 =>
if andb (complete_type cenv_cs t) (eqb_type t0 size_t)
then Some (Vptrofs (Ptrofs.repr (sizeof t)))
else None
| Ealignof t t0 =>
if andb (complete_type cenv_cs t) (eqb_type t0 size_t)
then Some (Vptrofs (Ptrofs.repr (alignof t)))
else None
end.

Lemma const_only_eval_expr_eq: forall {cs: compspecs} rho e v,
const_only_eval_expr e = Some v ->
eval_expr e rho = v.