Bug 513178 – www-client/firefox allow using --enable-unified-compilation

• Status: RESOLVED WONTFIX
• Product: Gentoo Linux

[Description Benjamin Peterson 2014-06-14 06:06:59 UTC]

Firefox has a build option, --enable-unified-compilation. This concatenates many C++ files together to improve both build time and compiler optimizations. (It does make the build more memory-hungry, though.) It would be nice if this flag could be easily enabled or was even the default.

I would have just passed this myself using ECONF_EXTRAS, but that doesn't seem to work for mozconfig ebuilds.

[Comment 1 Michał Górny 2014-06-14 07:23:18 UTC]

Does it really make sense nowadays, when we are going to have some LTO soon?

[Comment 2 Cănărău Constantin 2014-06-14 07:31:05 UTC]

Created attachment 378848 [details, diff]
Patch to firefox-30.ebuild

[Comment 3 Cănărău Constantin 2014-06-14 07:32:40 UTC]

Nice hint!

     Tue May 20 18:51:26 2014 >>> www-client/firefox-29.0.1
       merge time: 22 minutes and 30 seconds.

     Sat Jun 14 10:21:45 2014 >>> www-client/firefox-30.0
       merge time: 15 minutes and 9 seconds.

~ 30% compile time improvment

[Comment 4 Benjamin Peterson 2014-06-14 07:37:06 UTC]

As Cănărău demonstrated, the main advantage is improved compilation time, which is orthogonal to LTO.

[Comment 5 Cănărău Constantin 2014-08-02 12:06:45 UTC]

since v31 also Thunderbird support this configure option.
Compile time improvments are spectacular.

[Comment 6 Ian Stakenvicius (RETIRED) 2014-10-14 21:49:54 UTC]

I'm not certain I want to add this as an option, but what I may be able to do is add --enable-unified-compilation to the mozconfig when it exists in EXTRA_ECONF.  Would that suffice?

[Comment 7 Benjamin Peterson 2014-10-14 23:22:08 UTC]

That sounds fine.

[Comment 8 Ian Stakenvicius (RETIRED) 2014-10-15 14:25:20 UTC]

Ok, so in mozilla-overlay i updated the eclass so that it honors the value(s) specified in EXTRA_ECONF.  FYI, if you break it you pick up the pieces.

Right now, it just passes everything through to mozconfig; likely I will add a whitelist of allowable options at some point before this is added to the portage tree but we shall see.

[Comment 9 Ian Stakenvicius (RETIRED) 2014-10-16 14:15:34 UTC]

...this bug may soon be moot; if I'm reading configure.in from firefox-33 correctly, unified-compilation is enabled by default.  I'm going to look closer to confirm, and if that's the case then I'm going to leave it to upstream to set the default.  I may still consider enabling this option in 31ESR as well, but there are more urgent issues I have to sort out before I can test that fully.

[Comment 10 Ian Stakenvicius (RETIRED) 2014-10-16 15:14:12 UTC]

confirmed, mozilla 31.2 and 33 codebases both have unified compilation enabled by default and we would need to explicitly disable it in our configuration, which we don't.  Closing this one, as I don't want to open EXTRA_ECONF generally at this time.