I assume you meant a custom compiler backend? Read the Genode, Haiku or Nintendo Switch PR:
* [https://github.com/nim-lang/Nim/pull/5560](https://github.com/nim-lang/Nim/pull/5560) (Genode) * [https://github.com/nim-lang/Nim/pull/8542](https://github.com/nim-lang/Nim/pull/8542) (Haiku) * [https://github.com/nim-lang/Nim/pull/8069](https://github.com/nim-lang/Nim/pull/8069) (Switch)
