[llvm] [LoopUnroll] Skip remainder loop guard if skip unrolled loop (PR #156549)

[Mircea Trofin via llvm-commits]

mtrofin wrote:

> @jdenny-ornl , this patch caused more than 25% performance degradation due to additional spills/reloads. Could you please take a look? 
> 
> [f.zip](https://github.com/user-attachments/files/23277796/f.zip)
> 
> To reproduce compile the attached file  with O3 using flang or clang.

Drive-by comment - is the regression present when profiles are available?

https://github.com/llvm/llvm-project/pull/156549