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

[Ralf Jung via llvm-commits]

RalfJung wrote:

> `%v1 = load b256, ptr %a ; Freezed`

Loading at byte type cannot freeze. The entire point of the byte type is that it loads the underlying raw memory contents without changing them in any way.

I think the problem you are having is that LLVM does not have a coherent semantics (yet) so of course you can't implement one. That's one reason why having an interpreter like llubi is great: it can uncover issues of this sort. This particular issue is one we already knew about, but maybe there are more. :)

So anyway, you need to fundamentally decide whether the interpreter has undef or not. If it doesn't have undef, then uninit memory must be poison.

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