Function LLVMGetOrInsertNamedMetadata 

pub unsafe extern "C" fn LLVMGetOrInsertNamedMetadata(
    M: LLVMModuleRef,
    Name: *const c_char,
    NameLen: usize,
) -> LLVMNamedMDNodeRef

Retrieve a NamedMDNode with the given name, creating a new node if no such node exists.

@see llvm::Module::getOrInsertNamedMetadata()