I think that my change exposed a latent performance bug in the constraint solver. Let’s followup in a bug report:
https://bugs.swift.org/browse/SR-5669 <https://bugs.swift.org/browse/SR-5669> > On Aug 9, 2017, at 16:47, Mark Lacey <mark.la...@apple.com> wrote: > > > >> On Aug 9, 2017, at 11:33 AM, Arnold Schwaighofer <aschwaigho...@apple.com >> <mailto:aschwaigho...@apple.com>> wrote: >> >> Mark do you have suggestions for Dave? > > I’d suggest something similar to what Pavel said. My usual first step is to > look at the output of -Xfrontend -debug-constraints, which in cases like this > tends to be so verbose that you have to kill the compile after a little while > and a few megabytes of output and start reviewing that output. Key things to > look for are “(assuming”, which is printed for each disjunction choice, and > “(trying” which is printed before each attempt at trying a type binding. > > I took a quick look at this and based on the before/after output it looks > like perhaps an optimization that picks favored overloads is no longer firing > after your PR. As a result, rather than trying and successfully solving using > integer operations for the arithmetic and stopping there, we exponentially > attempt all combinations of all overloads of those operators. It would be > very interesting to understand why that is since based on the description I > would not expect your PR to have an impact on that. > > Mark > >> >>> On Aug 9, 2017, at 11:22 AM, David Zarzycki via swift-dev >>> <swift-dev@swift.org <mailto:swift-dev@swift.org>> wrote: >>> >>> Any tips on how to debug performance regressions? >>> >>> And as aside, if this test is critical enough to cause a revert, why isn’t >>> it in the public repo? >>> >> >> This is part of a larger internal test. >> >>> >>>> On Aug 9, 2017, at 14:04, Arnold Schwaighofer <notificati...@github.com >>>> <mailto:notificati...@github.com>> wrote: >>>> >>>> Hi Dave, >>>> I have reverted this commit because it broke internal bots. >>>> >>>> import Foundation >>>> class P { >>>> var x : Int = 0 >>>> var y : Int = 1 >>>> } >>>> >>>> let dist : (P, P) -> Double = { >>>> (p : P, s : P) -> Double in >>>> sqrt(Double((p.x-s.x)*(p.x-s.x) + (p.y-s.y)*(p.y-s.y))) >>>> } >>>> fails now with expression to complex. >>>> >>>> — >>>> You are receiving this because you authored the thread. >>>> Reply to this email directly, view it on GitHub >>>> <https://github.com/apple/swift/pull/11397#issuecomment-321334844>, or >>>> mute the thread >>>> <https://github.com/notifications/unsubscribe-auth/ABBbbrS4O6QyW6_j4ksVB-fo2EPtmbWVks5sWfSigaJpZM4Oxfg->. >>>> >>> >>> _______________________________________________ >>> swift-dev mailing list >>> swift-dev@swift.org <mailto:swift-dev@swift.org> >>> https://lists.swift.org/mailman/listinfo/swift-dev >>> <https://lists.swift.org/mailman/listinfo/swift-dev> >> >
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