[llvm] [TableGen] Fix computeRegUnitLaneMasks for ad hoc aliasing (PR #79835)

[Jay Foad via llvm-commits]

jayfoad wrote:

> Is it possible to ask review others about this PR in order to merge this? As I said at #79831 (comment), I think #79831 is not enough to cover the problem.

Sure, you can ask opinion from others, but personally I am not convinced that this is the best way to fix it.

> Recently the modification on live range (#88892) broke VE backend.

Do you have a test case for the new breakage? I'd like to take a look.

https://github.com/llvm/llvm-project/pull/79835