[Bug target/113257] -march=native or -mcpu=native are ineffective, but -march=native -mcpu=native works on arm64 M2 Ultra

[rearnsha at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113257

--- Comment #2 from Richard Earnshaw <rearnsha at gcc dot gnu.org> ---
For -mcpu=native, the manual says:

Additionally on native AArch64 GNU/Linux systems the value
@samp{native} tunes performance to the host system.  This option has no effect
if the compiler is unable to recognize the processor of the host system.

With similar working for -march=native

Since nobody has contributed patches to recognize the Apple Silicon cores, I
suspect that is the source of the problem.