[GHC] #10293: CallArity taking 20% of compile time

[GHC]

#10293: CallArity taking 20% of compile time
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        Reporter:  simonpj           |                   Owner:  nomeata
            Type:  bug               |                  Status:  closed
        Priority:  high              |               Milestone:  7.10.2
       Component:  Compiler          |                 Version:  7.10.1
      Resolution:  fixed             |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
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Comment (by AlekseyKliger):

 I've put together a Gist (by excising code from unbound-generics) that
 runs into this issue.
 I've not  tried the committed fix yet (don't have a GHC tree around), but
 perhaps someone else would like to play around with it:

 https://gist.github.com/lambdageek/c05cd379fe649600070c

 {{{
      $ ghc -c -O Alpha.hs
      $ ghc -c -v -O Calc.hs
      # note Calc.hs hangs on "Called arity analysis"
 }}}

 To make the compilation take longer, add some more branches to the Expr
 datatype - Generics are pretty good for building giant blobs of mutually
 recursive functions.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10293#comment:24>
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