[GHC] #8766: length [Integer] is twice as slow but length [Int] is 10 times faster

[GHC]

#8766: length [Integer] is twice as slow but length [Int] is 10 times faster
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        Reporter:  George                   |            Owner:
            Type:  bug                      |           Status:  new
        Priority:  normal                   |        Milestone:
       Component:  Compiler                 |          Version:  7.8.1-rc1
      Resolution:                           |         Keywords:
Operating System:  Unknown/Multiple         |     Architecture:
 Type of failure:  Runtime performance bug  |  Unknown/Multiple
       Test Case:                           |       Difficulty:  Unknown
        Blocking:                           |       Blocked By:
                                            |  Related Tickets:
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Comment (by nomeata):

 The improvement for `Int` is most likely from 82f56e5 (#876). But I guess
 the important point of the ticket is the regression for `Integer`.

 Maybe it is because of #8638? There might now be many checks whether the
 value fits in a `S#` that were not done before.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8766#comment:2>
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