[GHC] #13059: High memory usage during compilation

[GHC]

#13059: High memory usage during compilation
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        Reporter:  domenkozar        |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.2-rc2
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:  x86_64
 Type of failure:  Compile-time      |  (amd64)
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by dfeuer):

 I've bisected some more. It looks almost certain that the change causing
 this problem was 54b887b5abf6ee723c6ac6aaa2d2f4c14cf74060, "Improve
 typechecking of instance defaults", whose commit message mentions that it
 slows down a test that involves a very large number of instance
 declarations. That message claims that real programs don't have nearly so
 many, but perhaps `store` proves that wrong.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13059#comment:6>
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