[GHC] #13104: runRW# ruins join points

[GHC]

#13104: runRW# ruins join points
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        Reporter:  lukemaurer        |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.4.1
       Component:  Compiler          |              Version:  8.1
      Resolution:                    |             Keywords:  JoinPoints
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 Cool idea though.   See `Note [runRW magic]` in `MkId` for the main
 comment on this.

 I like the way that consumers correctly consume the result.

 We'd really like that NOINLINE to disapper right at the end somehow.

 One thing I like about `runRW#` is that it signals the magic very clearly;
 somehow a NOINLINE on a join point feels a bit too subtle.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13104#comment:6>
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