[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:
            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):
       Wiki Page:                    |
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Comment (by thoughtpolice):

 Just as an aside, I also applied the trick from comment:23 to cereal, and
 the results were almost unbelievable. The example given (comment:22)
 actually completely exhausts the simplifier tickets, so it essentially
 turns a non-compiling program into a compiling one that works in less than
 a second.

 https://github.com/GaloisInc/cereal/commit/94c87592d010fdb381c6a2dc963bbfcef99c3a27

 The result on the `binary-serialise-cbor` suite with this change is
 incredible. Just another data point - it would be useful to minimize
 `cereal` akin to `binary` in comment:22 and see the difference.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9630#comment:34>
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