[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:  patch
        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):

 Consider
 {{{
 joinrec j x y z = case x of
                    True -> <big>
                    False -> ...j...
 }}}
 where `<big>` does not mention `j`.  It looks to me that you don't even
 attempt to turn the whole of `<big>` into an exit point. Instead you
 recurse into it.  But why don't you?  The bigger the better!
 {{{
 join exit y = <big> in
 joinrec j x y z = case x of
                     True -> exit y
                     False -> ...j...
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14152#comment:37>
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