[llvm] [RISCV] Support select/merge like ops for bf16 vectors when have Zvfbfmin (PR #91936)

[Craig Topper via llvm-commits]

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@@ -1451,7 +1451,9 @@ foreach fvti = AllFloatVectors in {
                    fvti.RegClass:$rs2, 0, (fvti.Mask V0), fvti.AVL, fvti.Log2SEW)>;
 
   }
-  let Predicates = GetVTypePredicates<fvti>.Predicates in 
+
+  let Predicates = !listconcat(GetVTypePredicates<GetFpVTypeInfo<fvti>.Vti>.Predicates,
+                               GetVTypeScalarPredicates<fvti>.Predicates) in 
     def : Pat<(fvti.Vector (vselect (fvti.Mask V0),
                                     (SplatFPOp fvti.ScalarRegClass:$rs1),
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topperc wrote:

This patern isn't valid for bf16. If the scalar F register isn't properly nan-boxed it will create the wrong nan value in the vector domain.

https://github.com/llvm/llvm-project/pull/91936