[GHC] #12893: Profiling defeats stream fusion when using vector library

[GHC]

#12893: Profiling defeats stream fusion when using vector library
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        Reporter:  newhoggy          |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:  stream-fusion
                                     |  profiling
Operating System:  MacOS X           |         Architecture:  x86_64
 Type of failure:  Runtime           |  (amd64)
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 It's extremely difficult to combine (a) cost-centre profiling with (b)
 lots of optimisation.  It's a research question and GHC doesn't solve it.

 If you want unrestricted optimisation, I'm afraid you are stuck with the
 (much lower level) `ticky-ticky` profiling system.

 It'd be great to improve this, but I don't know how.

 Simon

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12893#comment:2>
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