[GHC] #2940: Do CSE after CorePrep

[GHC]

#2940: Do CSE after CorePrep
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    Reporter:  simonpj           |       Owner:  simonpj                
        Type:  bug               |      Status:  new                    
    Priority:  lowest            |   Milestone:  7.6.1                  
   Component:  Compiler          |     Version:  6.10.1                 
    Keywords:                    |          Os:  Unknown/Multiple       
Architecture:  Unknown/Multiple  |     Failure:  Runtime performance bug
  Difficulty:  Unknown           |    Testcase:                         
   Blockedby:                    |    Blocking:                         
     Related:                    |  
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Changes (by felixl):

 * cc: felix.lequen@… (added)


Comment:

 I think it would indeed be a good idea to do CSE after CorePrep (although
 I'm not at all a GHC expert), but after some Core dumping, there's a
 problem with this solution: the inliner seems to do his work ''before''
 CorePrep, so that with -O6 for example, some potential opportunities for
 CSE disappear… Well, that would still probably give better results than
 the current CSE, but for even more simplifications, it might be necessary
 to do inlining after CorePrep, I think.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2940#comment:9>
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