[GHC] #14461: Reuse free variable lists through nested closures

[GHC]

#14461: Reuse free variable lists through nested closures
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        Reporter:  tdammers          |                Owner:  alexbiehl
            Type:  task              |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.2.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  7258              |  Differential Rev(s):
       Wiki Page:  NestedClosures    |
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Comment (by alexbiehl):

 Ok, compiling with optimizations somewhat reduces the amount of updatable
 thunks. Possibly because of demand analysis.

 We must be careful to not share updatable thunks. I have to measure the
 impact but I suspect this will greatly reduce the effect of this
 transformation and we should think about a different scheme.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14461#comment:9>
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