(** ** Semantics of dynamic memory deallocation (free) *)
Inductive extcall_free_sem (ge: Senv.t):
list val -> mem -> trace -> val -> mem -> Prop :=
| extcall_free_sem_intro: forall b lo sz m m',
Mem.load Mptr m b (Ptrofs.unsigned lo - size_chunk Mptr) = Some (Vptrofs sz) ->
Ptrofs.unsigned sz > 0 ->
Mem.free m b (Ptrofs.unsigned lo - size_chunk Mptr) (Ptrofs.unsigned lo + Ptrofs.unsigned sz) = Some m' ->
extcall_free_sem ge (Vptr b lo :: nil) m E0 Vundef m'.

Lemma extcall_free_ok:
extcall_properties extcall_free_sem
(mksignature (Tptr :: nil) None cc_default).