[llvm] [RISCV][VLOPT] Skip EMUL if it is unknown before entering EMULAndEEWAreEqual (PR #139670)

[Piyou Chen via llvm-commits]

BeMg wrote:

> Would it be better if we just handle the nullopt EMUL case in `EMULAndEEWAreEqual`? Does it work if we just replace it with
> 
> ```c++
>   static bool EMULAndEEWAreEqual(const OperandInfo &A, const OperandInfo &B) {
>     return A.Log2EEW == B.Log2EEW && A.EMUL == B.EMUL;
>   }
> ```

Yes, It work.

https://github.com/llvm/llvm-project/pull/139670