[GHC] #11735: Optimize coercionKind

[GHC]

#11735: Optimize coercionKind
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        Reporter:  goldfire          |                Owner:  (none)
            Type:  task              |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.10.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by goldfire):

 I've taken the liberty of pushing directly to the `wip/tdammers/T11735`
 branch. I've done a bit of testing, and things seem OK, but a full
 testsuite run is surely warranted. Also, I've done no performance study of
 any kind, so that will surely need to be done, too.

 I'm curious to see what you find!

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11735#comment:42>
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