(** [negate_condition cond] returns a condition that is logically equivalent to the negation of [cond]. *)
Definition negate_condition (cond: condition): condition :=
match cond with
| Ccomp c => Ccomp(negate_comparison c)
| Ccompu c => Ccompu(negate_comparison c)
| Ccompimm c n => Ccompimm (negate_comparison c) n
| Ccompuimm c n => Ccompuimm (negate_comparison c) n
| Ccompf c => Cnotcompf c
| Cnotcompf c => Ccompf c
| Cmaskzero n => Cmasknotzero n
| Cmasknotzero n => Cmaskzero n
| Ccompl c => Ccompl(negate_comparison c)
| Ccomplu c => Ccomplu(negate_comparison c)
| Ccomplimm c n => Ccomplimm (negate_comparison c) n
| Ccompluimm c n => Ccompluimm (negate_comparison c) n
end.

Lemma eval_negate_condition:
forall cond vl m,
eval_condition (negate_condition cond) vl m = option_map negb (eval_condition cond vl m).