[llvm] [LV] Avoid redundant SCEVChecks on active lane mask (PR #171605)

[Luke Lau via llvm-commits]

lukel97 wrote:

> > Why don't we need the pointer overflow checks when we have an active lane mask?
> 
> MemChecks are still needed, and this patch doesn't change that?

Yes but I'm not familiar with the pointer overflow checks/SCEV checks which this patch removes. How does the active lane mask defend against that?

https://github.com/llvm/llvm-project/pull/171605