[GHC] #13739: Very slow linking of profiled executables

[GHC]

#13739: Very slow linking of profiled executables
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        Reporter:  duog              |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.2.1-rc2
      Resolution:                    |             Keywords:
Operating System:  Linux             |         Architecture:  x86_64
 Type of failure:  Compile-time      |  (amd64)
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by RyanGlScott):

 Oops, please ignore the noise about `-fwhole-archive-hs-libs` above. I
 forgot that the commit which introduced `-fwhole-archive-hs-libs`
 (a6874e546294173c166859769dd8054887a6ded7) didn't come until //after//
 283acec1d7307fdbd8cd7b3f1d984a036366d6b4 (Make split sections by default
 work again), so the times I got above were just from GHC erroring out. (I
 suppressed the stdout/stderr to avoid flooding my terminal, so I didn't
 notice this happening.)

 Also, an observation that I meant to make earlier is that I think that
 b207b536ded40156f9adb168565ca78e1eef2c74 (Generalize kind of the (->)
 tycon), which I singled out in comment:9, is a red herring. I think commit
 283acec1d7307fdbd8cd7b3f1d984a036366d6b4 (Make split sections by default
 work again) is the true culprit that causes a bad constant factor for each
 additional linked symbol, and commit
 b207b536ded40156f9adb168565ca78e1eef2c74 just happened to add a bunch of
 extra symbols. This is further evidenced by the fact that reverting
 283acec1d7307fdbd8cd7b3f1d984a036366d6b4 alone brings the link time back
 down to the same as what I get with GHC 8.0.2.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13739#comment:12>
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