[llvm] [RISCV] Add UnsupportedSchedZfhExceptForZfhmin for processors only support Zfhmin (PR #120196)

[Pengcheng Wang via llvm-commits]

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@@ -257,6 +257,31 @@ def : ReadAdvance<ReadFSqrt16, 0>;
 } // Unsupported = true
 }
 
+multiclass UnsupportedSchedZfhExceptForZfhmin {
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wangpc-pp wrote:

Thanks for reminding! 
Here I'd like to start the discussion: how should we handle the scheduling model of overlapped extensions like `Zfhmin` and `Zfh`? We know that only `Zfhmin` is mandatory in RVA23.
For current implementation, the scheduling model is not so fine-grained. For example, if we only support `Zfhmin`, then we don't need to define `UnsupportedSchedZfh`, but we still need to set `Unsupported` to true for arithmetic operations. And this is what we want to fix in this PR.

https://github.com/llvm/llvm-project/pull/120196