[GHC] #8173: GHC uses nub

[GHC]

#8173: GHC uses nub
-------------------------------------+-------------------------------------
        Reporter:  nh2               |            Owner:  leroux
            Type:  bug               |           Status:  closed
        Priority:  normal            |        Milestone:
       Component:  Compiler          |          Version:  7.6.3
      Resolution:  wontfix           |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  Compile-time      |       Difficulty:  Moderate (less
  performance bug                    |  than a day)
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
-------------------------------------+-------------------------------------
Changes (by leroux):

 * status:  new => closed
 * resolution:   => wontfix


Comment:

 Full nofib analysis of head, ordNub, and ordNub-cases (each ran twice):
 https://gist.github.com/leroux/6750216

 I took certain measures to make sure the nofib benchmarks would return
 "truer" results. I think you'll find the results much more reliable now.

 According to the results, sadly the 5% performance gain in compile time
 was complete bogus. Sorry. =(

 Snippet from https://gist.github.com/leroux/6750216#file-full-ordnub-
 analysis-L2880-L3467 (compile times):
 {{{

 Compile Times
 -------------------------------------------------------------------------------
         Program               head-0          head-1        ordNub-0
 ordNub-1  ordNub-cases-0  ordNub-cases-1
 -------------------------------------------------------------------------------
         -1 s.d.                -----           -1.6%           -1.6%
 -1.7%           -1.7%           -1.7%
         +1 s.d.                -----           +1.9%           +2.1%
 +1.6%           +2.0%           +1.7%
         Average                -----           +0.1%           +0.2%
 -0.0%           +0.1%           -0.0%

 }}}

 I'm closing this ticket now since there is no obvious improvement from
 replacing `nub` with `ordNub`.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8173#comment:12>
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