This page describes code generator ("codegen") in GHC. It is meant to reflect current state of the implementation. If you notice any inaccuracies please update the page (if you know how) or complain on ghc-devs.
You might occasionally hear about "old" and "new" code generator. GHC 7.6 and earlier used the old code generator. New code generator was being developed since 2007 and it was enabled by default on 31 August 2012 after the release of GHC 7.6.1. The first stable GHC to use the new code generator is 7.8.1 released in early 2014.