[GHC] #14844: SpecConstr also non-recursive function

[GHC]

#14844: SpecConstr also non-recursive function
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        Reporter:  nomeata           |                Owner:  (none)
            Type:  task              |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.5
      Resolution:                    |             Keywords:  SpecConstr
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by nomeata):

 I stared some more at the code, and learned:

  * Currently, !SpecConstr does specialize local non-recursive functions,
 but not top-level non-recursive functions. Comment in the source code
 about that: “Oddly, we don't seem to specialise top-level non-rec
 functions”. This can be fixed in `scTopBind`.
  * Together with loopification, SpecConstr only specialized everything as
 before if it is run twice, with a simplification in between. Otherwise, it
 refuses to specialize the outer non-recursive function because it does not
 see that its parameters are being scrutinized. I hope this can somehow be
 fixed in `SpecConstr`, so that it anticipates the state after
 simplifications.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14844#comment:5>
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