[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:  8.8.1
       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):

 Hmm, so when I skip the `-ticky`, the difference between the baseline and
 the `VarSet` version melts away:

 Baseline:
 {{{
         User time (seconds): 3.26
         System time (seconds): 0.09
         Percent of CPU this job got: 94%
         Elapsed (wall clock) time (h:mm:ss or m:ss): 0:03.53
 }}}

 VarSet:
 {{{
         User time (seconds): 3.25
         System time (seconds): 0.06
         Percent of CPU this job got: 96%
         Elapsed (wall clock) time (h:mm:ss or m:ss): 0:03.44
 }}}

 In fact, `VarSet` now ends up faster than `FV`.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14880#comment:77>
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