Lemma cl_step_unchanged_on ge c m c' m' b ofs : @cl_step ge c m c' m' -> Mem.valid_block m b -> ~ Mem.perm m b ofs Cur Writable -> Maps.ZMap.get ofs (Maps.PMap.get b (Mem.mem_contents m)) = Maps.ZMap.get ofs (Maps.PMap.get b (Mem.mem_contents m')).