[GHC] #14375: Implement with# primop

[GHC]

#14375: Implement with# primop
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        Reporter:  simonpj           |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.2.1
      Resolution:                    |             Keywords:  JoinPoints
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #14346            |  Differential Rev(s):  ​Phab:D4110
       Wiki Page:                    |
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Comment (by simonpj):

 Like I say, I'm thinking of this as STG only; an intermediate on the way
 to codegen.

 Yes there are still invariants.   To be a bit more precise
 `maskAsyncExceptions# j s`, `j` must be an arity-1 join point.  Always.

 But I am only thinking aloud here.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14375#comment:4>
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