[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 same is achieved with a much simpler change, namely the rule
 {{{
 "enumDeltaToInteger1"   [0] forall c n x . enumDeltaToIntegerFB c n x 1 =
 up_fb c n x 1
 }}}
 now I get 11.7s with `-fcall-arity` and 19.7s without, which is quite
 close the original 11.7s, and non-invasive enough to go into 7.8, I’d say.
 I’ll prepare a patch.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8766#comment:8>
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