[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 nomeata):

 I am wondering about the best place to perform this transformation. I
 could do it relatively easily as part of loopification (#14068), which I
 currently inserted between the occurrence analyser and the simplifier. But
 we also want to do it to `joinrec`s that are already `joinrec`s?

 The float out phase might also be a suitable place, since it – well –
 floats out expressions.

 Or maybe the simplifier itself (which has a notions of floating
 expressions, doesn’t it) can do it?

 Or should it be a pass of its own?

 Simon, what is your intuition here?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14152#comment:2>
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