[llvm] [AArch64] Stop reserved registers from being saved in prolog/epilog (PR #138448)

[Nikita Popov via llvm-commits]

nikic wrote:

This causes a 0.2% compile-time regression for O0-g builds (https://llvm-compile-time-tracker.com/compare.php?from=64082912a500d004c53ad1b3425098b495572663&to=26f97ee9aa413db240c397f96ddd5b0553a57d30&stat=instructions:u). Is it possible to query the reserved registers in a more efficient way?

https://github.com/llvm/llvm-project/pull/138448