Regarding Clang Custom Attributes, Visibility of Custom Attr in IR

Hi

i wish to add Attribute on Function so i added

def MutateFunction : InheritableAttr {
let Spellings = [GNU<“mutate_function_hint”>];
let Args = [UnsignedArgument<“SIndex”>,UnsignedArgument<“RIndex”>];
let Subjects = SubjectList<[Function], ErrorDiag>;
let Documentation = [Undocumented];
}

i have added function to hadle it, which simply adds attribute to Decl object

When i dump this declaration in SemaDeclAttr.cpp: handleMutateFunction i get

FunctionDecl 0xc9f9270 <kernel.cpp:6:12, line:7:1> col:1 k ‘void (class Rad::Nav &)’

-ParmVarDecl 0xc9f9000 <col:3, col:18> col:18 inParam ‘class Rad::Nav&’
`-MutateFunction 0xc9f92e0 <line:6:40, col:68> 50 10

But this attribute is not visible in final IR.
attribute #1 = { nounwind … }

How can i get it in #1?
Thanks in advance>