[Bug target/118328] Implement preserve_none for AArch64

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118328

--- Comment #13 from Sam James <sjames at gcc dot gnu.org> ---
The request here notwithstanding, bug report(s) with testcases for missed
opportunities in ipa-ra would be welcome too.

(btw, x86 has no_callee_saved_registers / no_caller_saved_registers too.)