[GHC] #14951: SpecContsr needs two runs when one should suffice

[GHC]

#14951: SpecContsr needs two runs when one should suffice
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        Reporter:  nomeata           |                Owner:  (none)
            Type:  task              |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.2.2
      Resolution:                    |             Keywords:  SpecConstr
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #14844            |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by nomeata):

 You are thinking one step ahead. But it does not need something analogous
 to demand signatures: The !SpecConstr code already gathers all calls to
 `f` and remembers them when it specializes `f`, so we can add the `ArgOcc`
 information there, without having the LetUp vs. LetDown dilemma.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14951#comment:3>
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