[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 simonpj):

 I can see that you get two copies of the same code, which CSE will
 presumably get rid of.  That might be worth trying to fix.

 But why does it lead to a 26x increase in compilation time? I'd expect it
 to be un-noticeable.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9630#comment:59>
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