[GHC] #13330: forkIO has inconsistent behavior under optimization

[GHC]

#13330: forkIO has inconsistent behavior under optimization
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        Reporter:  dfeuer            |                Owner:  dfeuer
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:  8.2.1
       Component:  Core Libraries    |              Version:  8.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  Other             |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D3189
       Wiki Page:                    |
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Comment (by dfeuer):

 It looks to me like the original work behind trying to be extra-clever
 about `catchException` demand analysis might be recoverable.
 Fundamentally, this has very little to do with `catch#` per se. The primop
 it suggests is a sort of `forceIO :: (State# s -> (# State# s, a)) ->
 (State# s -> (# State# s, a))`. The intuition behind this primop is that
 it reduces an `IO` action to something with precisely the form

 {{{#!hs
 \s -> case PRIMOP s of (# s', ... #) -> e
 }}}

 I don't know if this is actually implementable, but I think it's probably
 what all that fanciness in `Demand.hs` was trying to get at.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13330#comment:9>
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