[GHC] #13851: Change in specialisation(?) behaviour since 8.0.2 causes 6x slowdown

[GHC]

#13851: Change in specialisation(?) behaviour since 8.0.2 causes 6x slowdown
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        Reporter:  mpickering        |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.2.1
       Component:  Compiler          |              Version:  8.2.1-rc2
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 Based on this diagnosis, I don't think we should hold up the release.
 It's not a bug in pass X that can readily be fixed; it's the (very
 difficult) challenge of making correct inlining decisions.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13851#comment:6>
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