[llvm] [LV] Mask off possibly aliasing vector lanes (PR #100579)

[Sam Tebbs via llvm-commits]

SamTebbs33 wrote:

I've now fixed the comparison that's emitted since it should have been comparing to 0. See the Arm [WHILERW](https://developer.arm.com/documentation/ddi0602/2024-06/SVE-Instructions/WHILERW--While-free-of-read-after-write-conflicts-) instruction.

https://github.com/llvm/llvm-project/pull/100579