[RISCV] Prevent checkRVVTypeSupport from issuing more than 1 diagnostic. (#74950)

If vector isn't enabled at all, we might hit one of the earlier
diagnostics and the requires Zve32x diagnostic. The Zve32x diagnostic
would be redundant.

Author: topperc

clang/lib/Sema/SemaChecking.cpp

@@ -6181,22 +6181,22 @@ void Sema::checkRVVTypeSupport(QualType Ty, SourceLocation Loc, Decl *D) {
   if (((EltSize == 64 && Info.ElementType->isIntegerType()) || MinElts == 1) &&
       !TI.hasFeature("zve64x"))
     Diag(Loc, diag::err_riscv_type_requires_extension, D) << Ty << "zve64x";
-  if (Info.ElementType->isFloat16Type() && !TI.hasFeature("zvfh") &&
-      !TI.hasFeature("zvfhmin"))
+  else if (Info.ElementType->isFloat16Type() && !TI.hasFeature("zvfh") &&
+           !TI.hasFeature("zvfhmin"))
     Diag(Loc, diag::err_riscv_type_requires_extension, D)
         << Ty << "zvfh or zvfhmin";
-  if (Info.ElementType->isBFloat16Type() &&
-      !TI.hasFeature("experimental-zvfbfmin"))
+  else if (Info.ElementType->isBFloat16Type() &&
+           !TI.hasFeature("experimental-zvfbfmin"))
     Diag(Loc, diag::err_riscv_type_requires_extension, D) << Ty << "zvfbfmin";
-  if (Info.ElementType->isSpecificBuiltinType(BuiltinType::Float) &&
-      !TI.hasFeature("zve32f"))
+  else if (Info.ElementType->isSpecificBuiltinType(BuiltinType::Float) &&
+           !TI.hasFeature("zve32f"))
     Diag(Loc, diag::err_riscv_type_requires_extension, D) << Ty << "zve32f";
-  if (Info.ElementType->isSpecificBuiltinType(BuiltinType::Double) &&
-      !TI.hasFeature("zve64d"))
+  else if (Info.ElementType->isSpecificBuiltinType(BuiltinType::Double) &&
+           !TI.hasFeature("zve64d"))
     Diag(Loc, diag::err_riscv_type_requires_extension, D) << Ty << "zve64d";
   // Given that caller already checked isRVVType() before calling this function,
   // if we don't have at least zve32x supported, then we need to emit error.
-  if (!TI.hasFeature("zve32x"))
+  else if (!TI.hasFeature("zve32x"))
     Diag(Loc, diag::err_riscv_type_requires_extension, D) << Ty << "zve32x";
 }