[GHC] #4005: paraffins: slowdown of ca 2 with -O2

[GHC]

#4005: paraffins: slowdown of ca 2 with -O2
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    Reporter:  hwloidl       |        Owner:  igloo                             
        Type:  bug           |       Status:  new                               
    Priority:  high          |    Milestone:  6.12.3                            
   Component:  Compiler      |      Version:  6.12.1 RC1                        
    Keywords:  optimisation  |   Difficulty:                                    
          Os:  Linux         |     Testcase:  see attached (compile and run) log
Architecture:  x86           |      Failure:  Runtime performance bug           
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Comment(by hwloidl):

 Note that this program pL.hs is not exactly the paraffins code from the
 nofib suite.
 To parallelise it, I tweaked it, mainly using lists rather than arrays. So
 I'm not
 sure this is a case of regression.

 BTW, the parallelism on this program is quite nice: a parBuffer strategy
 rolling over
 a circular list that is generated by the program. Just FYI.

 Cheers,
 --
   HW

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4005#comment:4>
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