GCC 8 Will Let You -march=native Correctly On ARM/AArch64
This week -march=native now works on AArch64 as well as for ARM in general too.
That was followed up by allowing native for -mtune and -mcpu too on ARM.
Up to now on architectures where -march=native is unsupported, it would have no effect on the compiler's tuning/optimization behavior. The complete GCC ARM option documentation here.
GCC 8 should be officially released in the next month or two in the form of GCC 8.1 as the first stable release for this annual feature update to the GNU Compiler Collection.