[llvm] [ExtendLifetimes] Implement llvm.fake.use to extend variable lifetimes (PR #86149)

[Wolfgang Pieb via llvm-commits]

wolfy1961 wrote:

> I only skimmed the diff, but noticed there is no global isel lowering here. Were there any challenges in doing that or was it not considered?

IIRC, the original patch predated Global Isel, or else it was in a very early stage at the time, so it was simply not considered. 

> Our target of interest is X86, so I believe it was not considered. @wolfy1961 can correct me if I'm mis-remembering.

The patch wasn't meant to be specific to any target, although our efforts were concentrating on X86.



https://github.com/llvm/llvm-project/pull/86149