[GHC] #10400: Run time increases by 40% in fractal plotter core loop

[GHC]

#10400: Run time increases by 40% in fractal plotter core loop
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        Reporter:  saffroy           |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Compiler          |                 Version:  7.8.4
      Resolution:                    |                Keywords:
Operating System:  Linux             |            Architecture:  x86_64
 Type of failure:  Runtime           |  (amd64)
  performance bug                    |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
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Comment (by nomeata):

 Thanks! Looks interesting.

 Have you compared the RTS stats (pass `+RTS -s` to your binary)?

 Have you compiled your program with profiling enabled, and created a
 profile (`+RTS -p`), and compared that?

 Finally, you could compare the produce Core (compile with of `-ddump-
 simpl`) for obvious differences.

 Is there a noticable difference whether you use `take n (repeat ..)` or
 `replicate n ...`? If so, maybe some list fusion is happening or not
 happening. That should be observable in the RTS stats (number of
 allocations), or in the Core.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10400#comment:1>
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