[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):

 Argh! I was stupid again, in a different way. When I was trying out the
 old-style generics for `binary`, I forgot that my stage1 was 8.0.2, which
 is no good for that. When I used GHC 8.2.1 as the stage1, it built just
 fine. Using the merged classes ''and'' inlines to compile
 `Language.Haskell.Extension` takes 9 seconds, whereas with the split class
 and no inlines it takes 7. So I think this actually is fixed now. I'll put
 together a test case.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9630#comment:53>
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