[GHC] #8158: Replace IO manager's IntMap with a mutable hash table

[GHC]

#8158: Replace IO manager's IntMap with a mutable hash table
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        Reporter:  bos         |            Owner:
            Type:  feature     |           Status:  patch
  request                      |        Milestone:  7.8.1
        Priority:  normal      |          Version:  7.7
       Component:              |         Keywords:
  libraries/base               |     Architecture:  Unknown/Multiple
      Resolution:              |       Difficulty:  Easy (less than 1 hour)
Operating System:              |       Blocked By:
  Unknown/Multiple             |  Related Tickets:
 Type of failure:  Other       |
       Test Case:              |
        Blocking:              |
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Comment (by hvr):

 Now that I think of it, the motivation might be, that
 decrementing/incrementing a `IORef Int` might require to allocate new
 `I#`s and let the previous `I#` become garbage, as `IORef Int` doesn't
 unpack the `Int` value.

 (However, if that's really the case, isn't there some kind of lightweight
 (unpackable) "unboxed" IORef for integers types with
 [https://developer.gnome.org/glib/unstable/glib-Atomic-Operations.html
 atomic operations] provided by GHC somewhere?)

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8158#comment:6>
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