[llvm] [RISCV] Fix FP properties for Zvbdota instructions (PR #228737)

[Zeyi Xu via llvm-commits]

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@@ -59,15 +59,16 @@ defm VQWBDOTAS : VBdotVV<"vqwbdotas.vv", 0b101111>;  // Signed (funct6 = 0x2f)
 } // Predicates = [HasStdExtZvqwbdota8iOrZvqwbdota16i]
 
 // BF16 Batched Dot-Product Instructions
-let Predicates = [HasStdExtZvfwbdota16bf] in
+let Predicates = [HasStdExtZvfwbdota16bf], mayRaiseFPException = true in
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zeyi2 wrote:

[vfwbdota.vv](https://github.com/riscv/riscv-isa-manual/blob/c152059fd5db62fe5fe2b3e302bdfa130306e41c/src/zvdota.adoc?plain=1#L270-L285) uses the bulk-normalization scheme, which [permits RVBNA](https://github.com/riscv/riscv-isa-manual/blob/c152059fd5db62fe5fe2b3e302bdfa130306e41c/src/zvdota.adoc?plain=1#L482-L490). Since [RVBNA can raise invalid-operation and overflow exceptions](https://github.com/riscv/riscv-isa-manual/blob/a38e121306757164cdd664d7ffad158885d8b525/src/unpriv/rvbna.adoc?plain=1#L305-L307), I think this instruction needs mayRaiseFPException = true.

https://github.com/llvm/llvm-project/pull/228737