[GHC] #5075: CPR optimisation for sum types if only one constructor is used

[GHC]

#5075: CPR optimisation for sum types if only one constructor is used
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    Reporter:  batterseapower    |       Owner:  simonpj         
        Type:  feature request   |      Status:  patch           
    Priority:  normal            |   Milestone:  7.6.2           
   Component:  Compiler          |     Version:  7.0.3           
    Keywords:                    |          Os:  Unknown/Multiple
Architecture:  Unknown/Multiple  |     Failure:  None/Unknown    
  Difficulty:  Unknown           |    Testcase:                  
   Blockedby:                    |    Blocking:                  
     Related:                    |  
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Changes (by simonpj):

 * cc: nfrisby@… (added)


Comment:

 Indeed.  But the opportunity only arises after `SpecConstr`, and we don't
 currently run the demand/CPR analyser after `SpecConstr`, we run it
 before.

 Several other tickets (#6087, #5302, #6070) identify other opportunities
 that could be exploited by running the demand analyser again, late in the
 optimisation pipeline.

 Nick Frisby is planning to experiment with this.  Thanks for a new
 example.

 Simon

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5075#comment:12>
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