Function llfn_attrs_from_instance 

pub(crate) fn llfn_attrs_from_instance<'ll, 'tcx>(
    cx: &GenericCx<'ll, SCx<'ll>>,
    tcx: TyCtxt<'tcx>,
    llfn: &'ll Value,
    codegen_fn_attrs: &CodegenFnAttrs,
    instance: Option<Instance<'tcx>>,
)

Helper for FnAbi::apply_attrs_llfn: Composite function which sets LLVM attributes for function depending on its AST (#[attribute]) attributes.