[GHC] #8871: No-op assignment I64[BaseReg + 784] = I64[BaseReg + 784]; is generated into optimized Cmm

[GHC]

#8871: No-op assignment I64[BaseReg + 784] = I64[BaseReg + 784]; is generated into
optimized Cmm
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        Reporter:  kgardas           |            Owner:
            Type:  bug               |           Status:  new
        Priority:  normal            |        Milestone:
       Component:  Compiler          |          Version:  7.9
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  Other             |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
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Comment (by simonmar):

 Yes, this is just a missing optimisation.  I didn't implement it because I
 hadn't seen any code that needed it, until now.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8871#comment:5>
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