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

[GHC]

#1600: Optimisation: CPR the results of IO
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        Reporter:  simonmar          |            Owner:  nomeata
            Type:  task              |           Status:  new
        Priority:  lowest            |        Milestone:  7.6.2
       Component:  Compiler          |          Version:  6.6.1
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  Runtime           |       Difficulty:  Moderate (less
  performance bug                    |  than a day)
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:  #8598
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Comment (by nomeata):

 Small status update:

 My work on nested CPR has now reached somewhat conclusive state. The
 performance changes are not great, but it is still nice to have,
 especially if users who would re-write their code for performance would no
 longer have to do so.

 It should not go in for 7.8 – the gains are too small, and there still
 might be corner cases bugs. So I plan to merge it somewhen after 7.8.
 Until then, the branch `wip/nested-cpr` contains the changes in mostly
 cleaned-up, individually validated patches. I might occasionally rebase
 that branch to keep the conflicts small.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/1600#comment:40>
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