[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 simonpj):

 Quadrupling memory, adding 4Gb (that's a LOT of memory), is ridiculous!
 Yes, there are a dozen or two instance declarations, but only some use the
 default methods, and even if they do typechecking them should not take
 tons of memory.

 Something is mysterious here.

 I'd try `-dshow-passes` before and after, to see if the code size changes.
 It shouldn't change as a result of the patch, but with numbers as above I
 bet it does!  Then it'd be a question of seeing why.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13059#comment:7>
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