RFR: 8345298: RISC-V: Add riscv backend for Float16 operations - scalar [v4]

[Fei Yang]

On Thu, 6 Mar 2025 14:34:04 GMT, Hamlin Li <mli at openjdk.org> wrote:

> BTW, I just removed TestFloat16VectorConvChain test for riscv temporariely, as with this patch the ConvF2HF(AddF(ConvHF2F, ConvHF2F)) will be replaced by a ReinterpretHF2S(AddHF(ReinterpretS2HF, ReinterpretS2HF)).

Maybe we should also update the `@requires` of the test at the same time?
Currently, it says `| (os.arch == "riscv64" & vm.cpu.features ~= ".*zvfh.*")`.
Maybe we change `zvfh` into `zfh`?

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PR Comment: https://git.openjdk.org/jdk/pull/23844#issuecomment-2705343169