[author of the article] The RTL dump format does look a lot like Lisp, FWIW; see: https://gcc.gnu.org/onlinedocs/gccint/RTL.html https://gcc.gnu.org/onlinedocs

[author of the article] The RTL dump format does look a lot like Lisp, FWIW; see: https://gcc.gnu.org/onlinedocs/gccint/RTL.html https://gcc.gnu.org/onlinedocs/gccint/RTL.html or this article I wrote a while back on it: http://developerblog.redhat.com/2014/09/16/improving-gccs-internals/ http://developerblog.redhat.com/2014/09/16/improving-gccs-in... (This aspect of GCC is probably the oldest, written by RMS back in the late 1980s, I believe).