[GHC] #13566: Bigger core size in ghc8 compared to ghc7

[GHC]

#13566: Bigger core size in ghc8 compared to ghc7
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        Reporter:  pacak             |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       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 pacak):

 If you comment out

 {{{
     {-# SPECIALISE instance AdditiveGroup (Piecewise IntOfLogPoly4 Double)
 #-}
 }}}

 in Numeric/Polynomial/Piecewise.hs

 ghc7 version starts behaving similar to ghc8, at the same time
 AdditiveGroup instance is not used at all anywhere.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13566#comment:1>
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