https://www.geeksforgeeks.org/awk-command-unixlinux-examples/ – suppose you want to take the .s file generated by gcc -S and port the remaining assembly output to s-expressions. you should expect to be able to process it line-by-line. there’s indented parts, for instructions and allocations, and unindented parts for location markers.
https://people.csail.mit.edu/jaffer/SCM.html – a scheme interpreter to target, perhaps?
on examination of the target language, it appears identifiers may not include starting-dots. changing all “.”s to “dot-“s helps. there’s also the problem of string literals in the text, but close enough for, say…
https://bellard.org/otcc/ – the tiny c compiler from the obfuscated c code contest.
https://renenyffenegger.ch/notes/development/languages/C-C-plus-plus/GCC/options/S_uppercase/index – gcc options, navigable.