[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 have a lingering concern: ''why'' did the old `coercionKindRole` perform
 so miserably? In a call to `coercionRole`, the kind calculations should
 never be forced. So what takes up all the memory? Is it really just the
 tuples? If so, then we've discovered a major way to speed up other areas
 of GHC: convert tuples to be unboxed. Even better, we've discovered a
 major missing optimization, which could probably automate the unboxing
 somehow.

 So I wonder if there are more opportunities here. None of this changes the
 current direction of travel (caching is a good idea, regardless of my
 question here), but perhaps suggests another future line of inquiry.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11735#comment:35>
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