[swift-dev] -whole-module-optimization with -Onone

[Ben Asher]

Just running a quick trial before and after I made this change in our
project, we were previously seeing builds of our main target that took just
under 13min. With this hack, a clean debug build takes about 4.5min.

Ben

On Thu, Dec 1, 2016 at 1:33 PM, Ben Asher <benasher44 at gmail.com> wrote:

> Okay I think that worked! And just to clarify, you meant set
> SWIFT_OPTIMIZATION_LEVEL = -Owholemodule and OTHER_SWIFT_FLAGS = -Onone ?
>
> I'll file a radar this afternoon with some details and DM you the number.
>
> Thanks again!
>
> Ben
>
> On Thu, Dec 1, 2016 at 1:10 PM, Jordan Rose <jordan_rose at apple.com> wrote:
>
>> Xcode needs to know that you're building in WMO mode, so rather than
>> putting -whole-module-optimization in your "Other Swift Flags", put -Onone
>> there. It's an ugly hack but it should work in the near term.
>>
>> We do want to work to make this drastic speed difference go away, so if
>> you're able we (at Apple) would love to have a source drop of your Swift 3
>> project, for additional data on where the problems are. Mind filing a Radar?
>>
>> Best,
>> Jordan
>>
>>
>> > On Dec 1, 2016, at 11:51, Ben Asher via swift-dev <swift-dev at swift.org>
>> wrote:
>> >
>> > Hello! Someone recently tipped me off to using
>> -whole-module-optimization flag with -Onone for use during debug builds to
>> speed up compile times. In our project, the speedup feels quite dramatic,
>> but when it gets to the linking step (after compiling both Swift and Obj-C
>> in the project) it fails because ld can't find the individual object files
>> that normally get emitted during the debug-type build presumably because
>> -whole-module-optimization only emits one (and this isn't a normal
>> "-Owholemodule"-type build which works fine).
>> >
>> > I can't seem to reproduce this outside of Xcode, but I was curious if
>> anyone has tried this and knows of a workaround to get
>> -whole-module-optimization to work with -Onone in Xcode?
>> >
>> > I'm currently using Xcode 8.1 (App Store build) and Swift 3 on macOS
>> Sierra.
>> >
>> > Thanks!
>> >
>> > Ben
>> > _______________________________________________
>> > swift-dev mailing list
>> > swift-dev at swift.org
>> > https://lists.swift.org/mailman/listinfo/swift-dev
>>
>>
>
>
> --
> Ben
>



-- 
Ben
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.swift.org/pipermail/swift-dev/attachments/20161201/397f0326/attachment.html>