[llvm] RISC-V: Support vectorizing FMINIMUMNUM and FMAXIMUMNUM (PR #135727)

[Pengcheng Wang via llvm-commits]

wangpc-pp wrote:

Correct me if I am wrong. I think the description is wrong.

This is the spec description of vfmin/vfmax:

> The vector floating-point vfmin and vfmax instructions have the same behavior as the corresponding scalar floating-point instructions in version 2.2 of the RISC-V F/D/Q extension.

While in Zfa extension, it says:

>26.2. Minimum and Maximum Instructions
> The FMINM.S and FMAXM.S instructions are defined like the FMIN.S and FMAX.S instructions, except that if either input is NaN, the result is the canonical NaN.
> These instructions implement the IEEE 754-2019 minimum and maximum operations.

Based on my rough understanding, the vector vfmin/vfmax don' follow IEEE 754-2019, but IEEE 754-2008.

https://github.com/llvm/llvm-project/pull/135727