Hint Rewrite sem_cast_neutral_int using
  (auto;
   match goal with H: is_int ?i ?s ?v |- isVint ?v => apply (is_int_is_Vint i s v H) end) : norm.

Lemma eval_var_env_set: forall i t j v (rho: environ), eval_var i t (env_set rho j v) = eval_var i t rho.