[llvm] [RISCV][TTI] Support cost of f16 FCmp using zvfhmin in the absence of… (PR #89166)

[Philip Reames via llvm-commits]

https://github.com/preames commented:

Please precommit the extraction of rvv-fcmp-f16.ll so that the test changes are easier to follow.  You should probably also add a test line with no half support.  

https://github.com/llvm/llvm-project/pull/89166