Any doc/article/reference for the new Kotlin’s IR (intermediate representation)?

My mind was blown after seeing the kotlin-power-assert, and I’m eager to know about this (IR).

The sources are so wide (even though well documented almost one third of those), its hard to follow a path i.e. where to see and understand the things.

I was trying to find a way to write a compiler plugin which can modify the intermediate code, so that it will easily target multiplatform, but not able to find any quick-start or something for where to start or start looking at the sources.

If anybody know already about this, he/she can share his experience and help for how to get started (basically I want to know how to traverse all the function/classes and then some way to find linked/called functions, etc).