fn fat_lto(
cgcx: &CodegenContext,
prof: &SelfProfilerRef,
dcx: DiagCtxtHandle<'_>,
shared_emitter: &SharedEmitter,
tm_factory: TargetMachineFactoryFn<LlvmCodegenBackend>,
modules: Vec<FatLtoInput<LlvmCodegenBackend>>,
serialized_modules: Vec<(SerializedModule<ModuleBuffer>, CString)>,
symbols_below_threshold: &[*const c_char],
) -> ModuleCodegen<ModuleLlvm>