[GHC] #14684: combineIdenticalAlts is only partially implemented

[GHC]

#14684: combineIdenticalAlts is only partially implemented
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        Reporter:  mpickering        |                Owner:  sjakobi
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.6.1
       Component:  Compiler          |              Version:  8.2.2
      Resolution:                    |             Keywords:  newcomer
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D4542
       Wiki Page:                    |
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Comment (by simonpj):

 >  Should combineAlts get the same optimization as combineIdenticalAlts?
 Might combineAlts even be the better place to apply the optimization?

 Actually I think you are right -- CSE probably would be a better place.
 And then (because it doesn't happen all the time), you can probably do
 this stuff regardless of -O2.  (Having a flag might still be good just so
 you can switch it on and off at will.)

 I added some comments to Phab which will be useful either way.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14684#comment:11>
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