[llvm] [LLVM][SelectionDAG] Don't assume masked loads access all lanes in memory. (PR #192706)

[Nikita Popov via llvm-commits]

https://github.com/nikic approved this pull request.

LGTM

We should probably update visitMaskedStore to use upperBound instead of beforeOrAfter as well.

https://github.com/llvm/llvm-project/pull/192706