Hypothesis sem_swap:
forall c x y, sem (swap_comparison c) x y = sem c y x.

Lemma eval_compimm_swap:
forall le c a n2 x,
eval_expr ge sp e m le a x ->
exists v, eval_expr ge sp e m le (compimm default intsem (swap_comparison c) a n2) v
/\ Val.lessdef (sem c (Vint n2) x) v.