[GHC] #11445: Turn on SplitSections by default

[GHC]

#11445: Turn on SplitSections by default
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        Reporter:  ezyang            |                Owner:
            Type:  task              |               Status:  new
        Priority:  normal            |            Milestone:  8.2.1
       Component:  Build System      |              Version:  8.0.1-rc1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:  11285
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Description changed by ezyang:

Old description:

> This is a general tracking bug for what is blocking us from turning on
> `SplitSections` by default, implemented in #8405. Fixing this, and
> mandating use of the gold linker, will help solve #11285 (split objects
> make linking slow), and will make ghc-split unnecessary, mooting #9832.
>
> I encountered some misinformation while talking to people about this
> feature, regarding whether or not this feature only supported by Apple-
> style linkers (i.e. on Mac OS X)? On IRC I heard a claim made that
> `--split-sections` was only supported by Mac OS X. However, olsner
> pointed out that `-split-sections` on GHC was OUR reimplementation of the
> feature, and likely does not work on Mac OS X.
> https://github.com/snowleopard/shaking-up-
> ghc/issues/153#issuecomment-171078800  A later comment mentioned that
>
> So, can we turn on this feature by default? Does it subsume split-objs?
> Does it work on all the tier-1 platforms? It would be nice if bgamari,
> olsner and co could weigh in here. Thanks!

New description:

 This is a general tracking bug for what is blocking us from turning on
 `SplitSections` by default, implemented in #8405. Fixing this, and
 mandating use of the gold linker, will help solve #11285 (split objects
 make linking slow), and will make ghc-split unnecessary, mooting #9832.

 I encountered some misinformation while talking to people about this
 feature, regarding whether or not this feature only supported by Apple-
 style linkers (i.e. on Mac OS X)? On IRC I heard a claim made that
 `--split-sections` was only supported by Mac OS X. However, olsner pointed
 out that `-split-sections` on GHC was OUR reimplementation of the feature,
 and likely does not work on Mac OS X. https://github.com/snowleopard
 /shaking-up-ghc/issues/153#issuecomment-171078800  A later comment
 mentioned that

 So, can we turn on this feature by default? Does it subsume split-objs?
 Does it work on all the tier-1 platforms? It would be nice if bgamari,
 olsner and co could weigh in here. Thanks!

 Also, there are two different ways we can do this. One is we can turn it
 on by default in the GHC build system, so all the base libraries and GHC
 are built with it (but when you invoke ghc, it does NOT have split
 sections); the other is to have GHC always run split sections, so user
 code also compiles with it.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11445#comment:1>
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