[GHC] #8814: 7.8 optimizes attoparsec improperly

[GHC]

#8814: 7.8 optimizes attoparsec improperly
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        Reporter:  joelteon                 |            Owner:
            Type:  bug                      |           Status:  new
        Priority:  normal                   |        Milestone:
       Component:  Compiler                 |          Version:  7.8.1-rc1
      Resolution:                           |         Keywords:
Operating System:  MacOS X                  |     Architecture:  x86_64
 Type of failure:  Runtime performance bug  |  (amd64)
       Test Case:                           |       Difficulty:  Unknown
        Blocking:                           |       Blocked By:
                                            |  Related Tickets:  #8763
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Comment (by bos):

 I wrote a
 [https://github.com/bos/attoparsec/commit/b9a21b8e265949ec2d9541409b0a252aad3f638a
 workaround for this problem] that makes this particular performance
 regression vanish.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8814#comment:10>
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