[GHC] #4830: Simplifier does case-to-let too eagerly

[GHC]

#4830: Simplifier does case-to-let too eagerly
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    Reporter:  simonpj           |        Owner:                       
        Type:  bug               |       Status:  merge                
    Priority:  normal            |    Milestone:                       
   Component:  Compiler          |      Version:  7.0.1                
    Keywords:                    |     Testcase:  perf/should_run/T4830
   Blockedby:                    |   Difficulty:                       
          Os:  Unknown/Multiple  |     Blocking:                       
Architecture:  Unknown/Multiple  |      Failure:  None/Unknown         
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Changes (by simonpj):

  * status:  new => merge
  * testcase:  => perf/should_run/T4830


Comment:

 Fixed by
 {{{
 Wed Dec  8 17:22:51 GMT 2010  simonpj at microsoft.com
   * Make the case-to-let transformation a little less eager

   See Note [Case elimination: lifted case].
   Thanks to Roman for identifying this case.

     M ./compiler/simplCore/Simplify.lhs -19 +25
 }}}
 Please merge to stable branch.

 I've added a performance test.

 Simon

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4830#comment:1>
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