[GHC] #14880: GHC panic: updateRole

[GHC]

#14880: GHC panic: updateRole
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        Reporter:  RyanGlScott       |                Owner:  goldfire
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  8.2.2
  checker)                           |
      Resolution:                    |             Keywords:  TypeInType
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  crash or panic                     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #15076            |  Differential Rev(s):  Phab:D4769
       Wiki Page:                    |
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Comment (by tdammers):

 Replying to [comment:53 simonpj]:
 > Let me urge you to try it with an explicit accumulator, exactly as I
 wrote it.
 >
 > I recall that this made a very big difference for Bartosz.

 Tried that, but it seems to make absolutely no difference (that is,
 allocations go down by less than 0.004%).

 Also worth noting that `VarSet` here is based on `IntMap`, not `Map` as
 you quoted. Not sure if that changes anything, but maybe `IntMap` doesn't
 have the same problem `Map` has.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14880#comment:54>
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