[llvm] [AArch64] Legalize fp128 scalars as libcalls for G_FCMP (PR #98452)

[via llvm-commits]

Him188 wrote:

> There is quite a bit of code added to the legalizer that is not well tested. That is why I asked for a MIR file.

@tschuett The `llvm/test/CodeGen/AArch64/fcmp-fp128.ll` covers all the conditions so the added code should have almost complete test coverage. 

https://github.com/llvm/llvm-project/pull/98452