I've been working a bit on testing infrastructure for systematically improving swiftc compilation performance. Attached is a document summarizing both the machinery I put together, and an example (small) bug recently fixed, as a case study showing how to use it.
I'd like to encourage folks interested in swiftc compile times to take a read through; especially if you happen to have an existing bug, or pattern of bad performance you're seeing (or even have a hunch about), I'd be interested to know if a scaling test can capture it. I'll be working through some compilation performance bugs using this framework for the next while, so if anyone would like to collaborate on investigating something, let me know and I'd be happy to help.
CompilationPerformance.md (9.68 KB)