[GHC] #8742: Reuse scavenge_small_bitmap

[GHC]

#8742: Reuse scavenge_small_bitmap
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        Reporter:  Tarrasch          |            Owner:  Tarrasch
            Type:  task              |           Status:  patch
        Priority:  lowest            |        Milestone:  7.10.1
       Component:  Runtime System    |          Version:  7.6.3
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
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Comment (by simonmar):

 Don't go crazy here (also, it's not on your critical path!).  Yes it would
 be good to change uses of `nat` to `StgWord`, but there's no hurry.  If
 you want to do that as a separate patch then go ahead.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8742#comment:14>
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