[GHC] #15056: Wrappers inlined too late

[GHC]

#15056: Wrappers inlined too late
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        Reporter:  simonpj           |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.6.1
       Component:  Compiler          |              Version:  8.2.2
      Resolution:                    |             Keywords:
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 simonpj):

 The `fulsom` regression was in `Csg.calc`, which has nested join points.
 Several
 of them end up like this:
 {{{
  join j (x :: Double) = Board (case x of { D# y -> ... })
                               ...
  in ....(j (D# v))....
 }}}
 So the call to $j$ ends up with an explicit `(D# v)` argument, and
 `SpecConstr`
 should catch it.  But alas it does not because this happens nestedly, and
 `SpecConstr` is worried about exponential blowup.

 Why is this a regression?  Because something got inlined, that made
 a join point a bit bigger, which mean that the ''join point'' wasn't
 inlined.
 A classic inline-cascade problem.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15056#comment:4>
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