[GHC] #9669: Long compile time/high memory usage for modules with many deriving clauses

[GHC]

#9669: Long compile time/high memory usage for modules with many deriving clauses
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              Reporter:  snoyberg    |            Owner:
                  Type:  bug         |           Status:  new
              Priority:  normal      |        Milestone:
             Component:  Compiler    |          Version:  7.8.3
            Resolution:              |         Keywords:
      Operating System:  Linux       |     Architecture:  x86_64 (amd64)
       Type of failure:  Compile-    |       Difficulty:  Unknown
  time performance bug               |       Blocked By:
             Test Case:              |  Related Tickets:
              Blocking:              |
Differential Revisions:              |
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Comment (by simonpj):

 One thing that would help woul dbe if someone could characterise where the
 time is going. Build a profiled compiler (`GhcProfiled=YES` in your
 `build.mk`) and do some of the above tests.

 Using `-dshow-passes` also is good at showing if there is a big size blow-
 up anywhere.

 My fear is that these deriving clauses simply generate a lot of code, and
 that (naturally) takes a long time to compile.  My hope is that there is a
 "big eater" somewhere that we can kill.  But we need more information, and
 would appreciate help in getting it.

 Thanks

 Simon

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9669#comment:3>
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