[GHC] #4463: CORE notes break optimisation

[GHC]

#4463: CORE notes break optimisation
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    Reporter:  rl                |        Owner:                         
        Type:  bug               |       Status:  new                    
    Priority:  normal            |    Milestone:                         
   Component:  Compiler          |      Version:  7.1                    
    Keywords:                    |     Testcase:                         
   Blockedby:                    |   Difficulty:                         
          Os:  Unknown/Multiple  |     Blocking:                         
Architecture:  Unknown/Multiple  |      Failure:  Runtime performance bug
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Comment(by rl):

 I don't use them, a vector user ran into this. It's just that I ''think''
 we said they shouldn't affect optimisation (in particular, we made the
 rule matcher look through them) so I wanted to record this.

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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4463#comment:2>
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