[GHC] #8923: Add SmallArray# type

[GHC]

#8923: Add SmallArray# type
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        Reporter:  tibbe             |            Owner:  tibbe
            Type:  feature request   |           Status:  new
        Priority:  normal            |        Milestone:  7.10.1
       Component:  Compiler          |          Version:  7.9
      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 tibbe):

 I've written a patch (untested, but compiles) that adds a
 `StgSmallMutArrPtrs` type to the RTS. I would like a preliminary, high-
 level review of these changes to know if there are any major parts I'm
 missing. If this patch looks mostly OK I will go ahead and implement the
 compiler changes (i.e. type system and code generator changes) and write
 some tests.

 I'm was thinking of splitting the change into perhaps 3 commits for ease
 of reviewing: the RTS changes (roughly this patch), the compiler front-end
 changes (`Type` things), and finally the primops changes to code
 generator.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8923#comment:2>
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