[GHC] #14068: Loopification using join points

[GHC]

#14068: Loopification using join points
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        Reporter:  nomeata           |                Owner:  nomeata
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:  JoinPoints
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #13966 #14067     |  Differential Rev(s):  Phab:D3811
  #14827                             |
       Wiki Page:                    |
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Comment (by simonpj):

 >  Because if drop itself is in an inner loop, something like map (\n ->
 drop n xs) [0..1000], then we have to allocate a box for the the I# to
 wrap the argument.

 Ah, well that would ''also'' be true of any non-recursive function that
 was called in this way.

 I think you are claiming that all the extra allocation is due to boxing
 the arguments to a non-recursive function that is called repeatedly.
 That seems surprising, but perhaps it is true.

 If so, then I suppose a possible fix is to specialise non-recursive
 functions too.  Maybe that would be good in general; I'm not sure.   Might
 be worth trying...

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14068#comment:37>
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