[llvm] [CodeGen][Float8] Add float8 MVT type (PR #89901)

[via llvm-commits]

JinjinLi868 wrote:

> These are supposed to mirror IR types. How are these useful without the corresponding high level IR types?

on there https://github.com/llvm/llvm-project/pull/89900

https://github.com/llvm/llvm-project/pull/89901