[llvm] [TTI][BPF]: Undo specific transform-preventing passes and add one TTI hook (PR #97073)

[Dmitry Spikhalsky via llvm-commits]

Spikhalskiy wrote:

@inclyc Yes, thank you for the advice! We do consider using inline assembly as an alternative, but it has a serious disadvantage - relatively easy to write, but a madness for another dev to untangle down the line. It would be nice to keep it all in C. 

LLVM fork is problematic in another way though, as if upstream LLVM doesn’t work this out relatively soon, it’s a sure way for a legacy component that people will be afraid to touch and upgrade. 


https://github.com/llvm/llvm-project/pull/97073