Notation val_inject:=Val.inject.(*A value that is (if its a pointer) not dangling wrt m - a condition
 like this will probably be need to imposed on after-external return
 values (and thus also on the values returned by halted)*)
Definition val_valid (v:val) (m:mem):Prop :=
     match v with Vptr b ofs => Mem.valid_block m b | _ => True
     end.

Lemma inject_valvalid_1: forall (j : meminj) (m1 m2 : mem), Mem.inject j m1 m2 -> forall v1 : val, val_valid v1 m1 -> forall v2 : val, val_inject j v1 v2 -> match v1 with Vundef => True | _ => val_valid v2 m2 end.