Definition mem_respects_readonly {F V} (ge : Genv.t F V) m :=
forall b gv, Genv.find_var_info ge b = Some gv ->
gvar_readonly gv && negb (gvar_volatile gv) = true ->
Genv.load_store_init_data ge m b 0 (gvar_init gv) /\
Mem.valid_block m b /\ (forall ofs : Z, ~ Mem.perm m b ofs Max Writable).

Lemma free_contents:
forall m b lo hi m' b' ofs,
Mem.free m b lo hi = Some m' ->
~adr_range (b,lo) (hi-lo) (b',ofs) ->
ZMap.get ofs (PMap.get b' (Mem.mem_contents m)) =
ZMap.get ofs (PMap.get b' (Mem.mem_contents m')).