[GHC] #7258: Compiling DynFlags is jolly slow

[GHC]

#7258: Compiling DynFlags is jolly slow
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        Reporter:  simonpj           |                Owner:  simonpj
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.6.1
      Resolution:                    |             Keywords:  deriving-perf
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by tdammers):

 It seems that for the misbehaving examples, the offensive cost centre is
 Stg2Stg. As code size increases, CPU time for this cost centre grows
 disproportionally in the `read` and `show` examples, while it remains
 below 40% for the well-behaved ones.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7258#comment:77>
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