Code compiled for arm64 much slower than for x86_64

[tschuett]

Enabling GlobalISel for Apple AArch64 platforms

We at Apple have been working on bringing up GlobalISel with the AArch64 target for a number of years now. Last year we presented our progress on this for all opt levels and stated our intentions to enable it for Apple platforms in the near future. Please see the talk video here if you’re interested in some of the work we did to make it competitive with SelectionDAG. For the past few months we’ve been working on qualifying GlobalISel on internal Apple software, fixing issues as we discover them…

Apple switched the Code Generator for Arm64 with clang 14? My Apple clang seems to support -fno-global-isel.