[GHC] #1600: Optimisation: CPR the results of IO

[GHC]

#1600: Optimisation: CPR the results of IO
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        Reporter:  simonmar          |                Owner:  (none)
            Type:  task              |               Status:  new
        Priority:  lowest            |            Milestone:
       Component:  Compiler          |              Version:  6.6.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #8598             |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by akio):

 Replying to [comment:68 simonpj]:
 > Akio, I've fixed that wrapper issue.

 Thank you!

 >
 > What's next on this ticket?

 After rebasing the branch on top of your fix, the nofib improvements are
 again consistent but very small:

 {{{
 --------------------------------------------------------------------------------
         Program           Size    Allocs   Runtime   Elapsed  TotalMem
 --------------------------------------------------------------------------------
             hpg          +0.2%     -1.1%     0.212     0.212      0.0%
           infer          +0.3%     -1.2%     0.054     0.054      0.0%
           solid          +0.3%     -6.6%     0.181     0.181      0.0%
          sphere          +0.3%     -1.7%     0.086     0.086      0.0%
 --------------------------------------------------------------------------------
             Min          +0.2%     -6.6%    -23.2%    -23.4%    -19.2%
             Max          +0.7%     +0.1%    +16.3%    +16.2%      0.0%
  Geometric Mean          +0.3%     -0.1%     -0.1%     -0.1%     -0.3%
 }}}

 The branch can perform nested CPR in simple cases, but it fails to
 transform some cases I would like it to. Currently I'm trying to make
 `extendSigsWithLam` a bit more aggressive by allowing it to generate
 nested CPR information.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/1600#comment:69>
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