[GHC] #15519: Minor code refactoring leads to drastic performance degradation

[GHC]

#15519: Minor code refactoring leads to drastic performance degradation
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        Reporter:  danilo2           |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:  8.8.1
       Component:  Compiler          |              Version:  8.4.3
      Resolution:                    |             Keywords:  SpecConstr
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 >     This is very interesting. Would you be so nice and tell me jsut a
 little more aobut it - where can I learn about it and why such design
 decisions were made?

 I'm afraid I have never written a paper about eta-expansion, despite its
 importance to GHC.

 There are extensive Notes in
 * `CoreArity.hs` (which is all about arity and eta expansion)
 * `SimplUtils.hs` (around `tryEtaExpandRhs` and `tryEtaReduce`)

 I think that's the best I can do without a big investment

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15519#comment:18>
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