[llvm] [llubi] Add support for byte types (PR #200672)

[Nikita Popov via llvm-commits]

nikic wrote:

I agree that undef should not be frozen when loading byte types.

But more generally, I think precisely modelling undef semantics is simply a non-goal for llubi. It would be a lot of complexity for something that is going away. We just crudely approximate it by freezing early, which e.g. allows to detect non-deterministic reductions due to loads from uninit memory.

I don't think we should waste any time on undef handling in llubi. The problems with it are well-understood and will only be fixed by removing it.

https://github.com/llvm/llvm-project/pull/200672