[GHC] #9630: compile-time performance regression (probably due to Generics)

[GHC]

#9630: compile-time performance regression (probably due to Generics)
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        Reporter:  hvr               |                Owner:  dfeuer
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.2.1
       Component:  Compiler          |              Version:  7.9
      Resolution:                    |             Keywords:  deriving-
                                     |  perf, Generics
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #9583, #10293,    |  Differential Rev(s):
  #13059, #10818                     |
       Wiki Page:                    |
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Comment (by dfeuer):

 I think the original issue is fixed. To be extra clear, the original issue
 was that it was very slow to compile `Language.Haskell.Extension` from
 `Cabal`. I was able to reproduce this using Cabal at commit
 [https://github.com/haskell/cabal/commit/eaf2aae18603965ff668384b391fcaa14de19823
 eaf2aae18603965ff668384b391fcaa14de19823]. The problem there appeared in
 GHC commit  b9e49d3e9580e13d89efd1f779cb76f610e0d6e0, which added 1024
 specialization rules for said module. The problem is now gone.

 It looks to me as though ezyang's test case in comment:22 doesn't actually
 relate to the regression; I don't see it moving terribly much from 7.8 to
 7.10 or from 7.10 to 8.2. It seems to be looking at other issues. I will
 try to see how those have shifted.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9630#comment:48>
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