It’s a bit orthogonal to monomorphization, but I believe C++ compilers can occasionally deduplicate identical template instantiations, where “identical” means they compile to the same assembly even though the types are different.
One next step that I don't think C++ compilers do yet is deduplicate functions that differ only in constants used or functions called. This could help with std::sort-style functions where the outer algorithm can work on generic pointers and only the comparison is a call to a different function.
Monomorphization would ideally be treated the same way.
Yes, there are aspects of C++ that make that so difficult that it's just not realistic, but really I was only bringing up C++ because the parent poster certainly meant the C++ std::sort. The same argument could also be applied to other languages that have less baggage, e.g. Rust comes to mind.