Rat is a simple compiler backend focused on ease of use. It's inspired by LLVM but focused on more novel approaches (ie. the Sea of Nodes IR) and being much easier to understand (the backend library is currently ~13k LoC). To this end, rat focuses on bringing ~70% of LLVM's performance with only a fraction of LLVM's complexity. You can find the documentation here.
$ ./build.sh
$ ./test.sh
$ ./bench.sh