[compiler-rt] [libcxx] [llvm] compiler-rt: Introduce runtime functions for emulated PAC. (PR #133530)

[Anatoly Trosinenko via llvm-commits]

atrosinenko wrote:

Hmm, my guess seems to be wrong, as both Neoverse N2 and V2 support FEAT_FPAC, if I understand corresponding TRMs correcly.

> The feature detection on Windows might not set all the same feature flags as the feature detection on Linux though.

@mstorsjo As far as I see, this patch does not ask the OS about supported CPU features, it just executes a backward-compatible XPACLRI instruction and checks whether it behaves as NOP or not.

https://github.com/llvm/llvm-project/pull/133530