[GHC] #8315: Improve specialized Hoopl module

[GHC]

#8315: Improve specialized Hoopl module
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       Reporter:  jstolarek         |             Owner:
           Type:  task              |            Status:  new
       Priority:  low               |         Milestone:
      Component:  Compiler          |           Version:  7.7
       Keywords:                    |  Operating System:  Unknown/Multiple
   Architecture:  Unknown/Multiple  |   Type of failure:  None/Unknown
     Difficulty:  Unknown           |         Test Case:
     Blocked By:                    |          Blocking:
Related Tickets:                    |
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 GHC uses Hoopl to perform some of the Cmm-to-Cmm optimization passes, but
 instead of relying directly on Hoopl library GHC uses its own specialized
 module (see [[GhcFile(compiler/cmm/Hoopl/Dataflow.hs)]]). Interface of
 that module, as well as its internal implementation can be improved. Right
 now interface places responsibility of maintaining some of the invariants
 on user. It also ignores differences between forward and backward
 analysis. [http://ghc.haskell.org/trac/ghc/wiki/Hoopl/Cleanup This wiki
 page] gives full detail about proposed design changes.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8315>
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