[llvm] [X86] Support EGPR (R16-R31) for APX (PR #70958)

[Nikita Popov via llvm-commits]

nikic wrote:

I reran compile-time tests after https://github.com/llvm/llvm-project/pull/70222:

[Original results](https://llvm-compile-time-tracker.com/compare.php?from=b5dffd4957dfb58c73e168a3d9b6967f03b23a6c&to=feea5db01360b477b8cf2df03abfa9fc986633d5&stat=instructions%3Au)
[New results](https://llvm-compile-time-tracker.com/compare.php?from=6c320b434d249c0d5692cbecc0e67ec22d659b7e&to=502ddafd0342160aefe92f3dced65865fad20746&stat=instructions:u)

It looks like the regression for optimized builds has been partially mitigated, but the regression for unoptimized builds is still about the same (e.g 0.7% on sqlite3).

https://github.com/llvm/llvm-project/pull/70958