Apologies for not starting off with system info: macOS Sierra (10.12.0), Xcode 8.0 (from the App Store).
I'll try with Xcode 8.1 beta this afternoon and report back. Ill also open a ticket for improving -debug-time-function-bodies if I can confirm anything. Thanks! Ben On Wed, Oct 5, 2016 at 1:00 PM, Mark Lacey <mark.la...@apple.com> wrote: > > On Oct 4, 2016, at 2:38 PM, Ben Asher via swift-dev <swift-dev@swift.org> > wrote: > > Hello! I work with a large project (~900 .swift files and more .m files). > We have a nightly job that compiles the app and calls out function bodies > (using -debug-time-function-bodies) that are slower than 100ms to > compile. Since upgrading to Swift 3, the number of trouble function bodies > has one from > 150 to < 20, so we're really happy about that! The only > issue though is that build time overall increased by ~1 min (amount of time > to build all targets before automatically merging to master in our > integration build). > > > Is this using a particular release of Xcode (8.0 or an 8.1 beta?), or with > one of the toolchain builds from swift.org? > > Xcode 8.1 beta 2 includes some type checker performance improvements which > might have an impact here. > > > To dig into this further, we've started a new nightly job that builds the > app using the -debug-time-compilation flag, and using that we've found that > some files take as long as 2-3 seconds to compile. But, there's no targeted > output to help us get this down via the -debug-time-function-bodies flag > (i.e. no function bodies that we can refactor to get compile times much > faster). > > > One thing to look out for here is that I believe there are some cases > where -debug-time-function-bodies isn’t reporting type checking time. From > my (potentially faulty) recollection, things like let bindings with > literals or closures on the right hand side do not show up in the > -debug-time-function-bodies output, and depending on the specifics of the > expression these can sometimes take a long time to type check. When these > appear within the body of another type declaration they can end up getting > type checked multiple times during a full project build, and that time can > add up. > > I don’t believe there is a bug open for improving > -debug-time-function-bodies to help diagnose this, but opening a bug would > be appreciated if you can confirm that this is the case, and of course > patches to fix it are definitely welcome as well. > > Mark > > We can see that most of the time is spent in "Type checking / Semantic > analysis" for these problem files, but we don't currently have any way of > knowing what that means. It feels like we've exhausted the available > options at this point (unless there are other flags I'm missing) in terms > of existing actionable debugging/profiling/reporting, so now our question > is this: what kind of reports would Swift maintainers be interested in > seeing in terms of output from profiling tools, etc. to help debug/diagnose > these slow compile issues? We're willing to devote time to tooling to help > generate such reports and file bugs. > > Thanks! > > Ben > _______________________________________________ > swift-dev mailing list > swift-dev@swift.org > https://lists.swift.org/mailman/listinfo/swift-dev > > > -- -Ben
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