Function generic_simd_intrinsic 

fn generic_simd_intrinsic<'ll, 'tcx>(
    bx: &mut GenericBuilder<'_, 'll, FullCx<'ll, 'tcx>>,
    name: Symbol,
    fn_args: GenericArgs<'tcx>,
    args: &[OperandRef<'tcx, Value<'ll>>],
    ret_ty: Ty<'tcx>,
    llret_ty: Type<'ll>,
    span: Span,
) -> Result<Value<'ll>, ErrorGuaranteed>