[GHC] #14152: Float exit paths out of recursive functions

[GHC]

#14152: Float exit paths out of recursive functions
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        Reporter:  nomeata           |                Owner:  (none)
            Type:  task              |               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:  #14137 #10918     |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 > the simplifier seems to throw away the idOccInfo.

 That's by design.  The occ-info after simplification isn't necessarily
 valid.  E.g.
 {{{
 x = e
 f = \y. ...x...
 y = ...(f 1)...(f 2)...
 }}}
 Currently x occurs once, but after inlining `f` twice, `x` occurs twice.
 So the simplifier carefullly deletes it.   (Except for robust info like
 "this lambda binder is dead".)

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14152#comment:13>
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