[GHC] #13916: Optimizations create run time seg faults

[GHC]

#13916: Optimizations create run time seg faults
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        Reporter:  newthin           |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:  8.2.2
       Component:  Compiler          |              Version:  8.0.2
  (CodeGen)                          |
      Resolution:                    |             Keywords:  optimization
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  Runtime crash     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by bgamari):

 I think I see: `foldlM_loop_a45q` places a `C(S)` demand on its second
 argument and called with this argument being `retry#`. `retry#` has a
 divergent demand result (namely `Demand.botRes`). This is likely how the
 analyzer concludes that `takeEnv` will diverge.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13916#comment:18>
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