[GHC] #8905: Function arguments are always spilled/reloaded if scrutinee is already in WHNF

[GHC]

#8905: Function arguments are always spilled/reloaded if scrutinee is already in
WHNF
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        Reporter:  tibbe                    |            Owner:
            Type:  bug                      |           Status:  new
        Priority:  normal                   |        Milestone:
       Component:  Compiler                 |          Version:  7.9
      Resolution:                           |         Keywords:
Operating System:  Unknown/Multiple         |     Architecture:
 Type of failure:  Runtime performance bug  |  Unknown/Multiple
       Test Case:                           |       Difficulty:  Unknown
        Blocking:                           |       Blocked By:
                                            |  Related Tickets:
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Comment (by simonmar):

 Yeah, it is somewhat by design (to get smaller code), but you're quite
 right that we should have faster code for the common case.  I'll look into
 it and see if we can improve things.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8905#comment:4>
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