[clang] [RISCV][clang] Add Zvfbfmin C intrinsics support (PR #79618)

[Craig Topper via cfe-commits]

================
@@ -1883,6 +1883,12 @@ let Log2LMUL = [-3, -2, -1, 0, 1, 2] in {
   def vfncvt_rtz_x_f_w : RVVConvToNarrowingSignedBuiltin<"vfncvt_rtz_x">;
   def vfncvt_rod_f_f_w : RVVConvBuiltin<"v", "vw", "xf", "vfncvt_rod_f">;
 }
+
+// Zvfbfmin - Vector convert BF16 to FP32
+let Log2LMUL = [-2, -1, 0, 1, 2],
----------------
topperc wrote:

We can probably do something like what is done for Zvfh in SemaRISCVVectorLookup.cpp. In practice, it probably doesn't matter match since you can't declare a bfloat16 vector with Zvfhbfmin so you can't use the intrinsic even if it was declared.

```
      if (BaseType == BasicType::Float16) {                                      
        if ((Record.RequiredExtensions & RVV_REQ_Zvfhmin) == RVV_REQ_Zvfhmin) {  
          if (!TI.hasFeature("zvfhmin"))                                         
            continue;                                                            
        } else if (!TI.hasFeature("zvfh")) {                                     
          continue;                                                              
        }                                                                        
      } 
```

https://github.com/llvm/llvm-project/pull/79618