@whitequark Someone did this a few years back. They wrote an AWS Lambda that was clang. You needed to do the preprocessing locally, which limited the scaling.
The thing I pondered after seeing it was to make the local clone a file share that I could mount over CIFS and also mount in the function and make the build directory a similar share where only the final build products needed to be exported, so I could run the compiler and linker steps entirely as cloud functions. I didn’t every get around to implementing it, so I didn’t have a solution to things like TableGen.