[GHC] #8598: IO hack in demand analyzer gets in the way of CPR

[GHC]

#8598: IO hack in demand analyzer gets in the way of CPR
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        Reporter:  nomeata           |            Owner:
            Type:  task              |           Status:  new
        Priority:  normal            |        Milestone:
       Component:  Compiler          |          Version:  7.6.3
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
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Comment (by nomeata):

 Nofib believes that this is a good change (runtime not reliable, as I ran
 other stuff in parallel):

 {{{
 --------------------------------------------------------------------------------
         Program           Size    Allocs   Runtime   Elapsed  TotalMem
 --------------------------------------------------------------------------------
            fft2          -0.0%     -0.1%      0.10      0.10     +0.0%
          mandel          -0.0%     -9.2%      0.10      0.10     +0.0%
        nucleic2          -0.0%     -0.3%      0.10      0.10     +0.0%
 --------------------------------------------------------------------------------
             Min          -0.1%     -9.2%     -3.4%     -4.1%     +0.0%
             Max          -0.0%     +0.0%    +18.5%    +19.3%     +0.0%
  Geometric Mean          -0.0%     -0.1%     +1.7%     +1.6%     -0.0%
 }}}

 I’ll push it to branch `wip/T8598` for review.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8598#comment:4>
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