[GHC] #2132: Optimise nested comparisons

[GHC]

#2132: Optimise nested comparisons
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    Reporter:  simonpj           |        Owner:                         
        Type:  bug               |       Status:  patch                  
    Priority:  low               |    Milestone:  7.4.1                  
   Component:  Compiler          |      Version:  6.8.2                  
    Keywords:                    |     Testcase:                         
   Blockedby:                    |   Difficulty:  Unknown                
          Os:  Unknown/Multiple  |     Blocking:                         
Architecture:  Unknown/Multiple  |      Failure:  Runtime performance bug
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Comment(by simonmar):

 Wow, there's quite a lot of code here.  Simon: we need to review and
 decide what to do.  Somehow this optimisation feels similar to what the
 simplifier already does with case expressions (eliminating redundant
 cases, and branches that can't match), and perhaps it ought to be
 incorporated into the simplifier.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2132#comment:14>
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