[llvm] Add more generic `half`/`bfloat` tests (NFC) (PR #157211)

[Nikita Popov via llvm-commits]

nikic wrote:

> Regardless, it would be quite useful to have a test tracking the fixing of `half` FMA.

This is already covered by this RISCV test for example: https://github.com/llvm/llvm-project/blob/8ae3aeaca0b2de1702c90b120ef4b57accef9a3c/llvm/test/CodeGen/RISCV/half-arith.ll#L1097

These cross-target tests are useful for testing the migration to TypeSoftPromoteHalf -- they are not the place to test all possible half-float related issues.

> Would merging `half-op.ll` into `half.ll` by removing BPF from `half.ll` and leaving a comment pointing to a BPF specific test that just tests operations that BPF supports (since BPF can only use operations that don't require libcalls) resolve your concerns?

Yes, that's fine.

https://github.com/llvm/llvm-project/pull/157211