[llvm] [LV][NFC] Remove simplifycfg pass from RUN lines (PR #195817)

[David Sherwood via llvm-commits]

david-arm wrote:

> > but it does make the tests run slower.
> 
> By how much? I can't imagine the overhead of running simplifycfg on such cases is high. I wouldn't be surprised if process startup overhead dominates in some cases.

Yeah maybe it's not slower by much, but then I personally don't see much real value to running simplifycfg on the tests either so I figured the tests are just simpler without it.

Perhaps this is just me, but I also find it harder to map the expected vectoriser output to the CHECK lines when there are multiple passes being run. Also, there is the possibility of additional passes masking bugs or inefficiencies in the vplan/generatd IR. This is certainly true for additional instcombine passes, where I've spotted some vplan optimisations that we're missing because instcombine is doing them for us.

https://github.com/llvm/llvm-project/pull/195817