[GHC] #12059: Add primop to query for pinned-ness of a ByteArray

[GHC]

#12059: Add primop to query for pinned-ness of a ByteArray
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        Reporter:  bgamari           |                Owner:
            Type:  feature request   |               Status:  patch
        Priority:  normal            |            Milestone:  8.2.1
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D2217
       Wiki Page:                    |
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Description changed by bgamari:

@@ -5,0 +5,3 @@
+
+ This, for instance, allows one to construct a `ByteString` from a
+ `ByteArray` in an opportunistically zero-copy manner.

New description:

 It would be useful to have,
 {{{#!hs
 isPinnedByteArray# :: MutableByteArray# -> Int#
 }}}

 This, for instance, allows one to construct a `ByteString` from a
 `ByteArray` in an opportunistically zero-copy manner.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12059#comment:2>
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