[GHC] #16039: 'GHC.Magic.noinline <var>' should not float out

[GHC]

#16039: 'GHC.Magic.noinline <var>' should not float out
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        Reporter:  heisenbug         |                Owner:  heisenbug
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.8.1
       Component:  Compiler          |              Version:  8.2.1
      Resolution:                    |             Keywords:  FloatOut
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #15155            |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by heisenbug):

 Thanks, I did not have this `exprIsTrivial` change on my radar yet.

 So far I have:
 {{{#!hs
 notWorthFloating e abs_vars
   = go e (count isId abs_vars)
   where
     go (Var {}) n    = n >= 0
     go (Lit lit) n   = ASSERT( n==0 )
                        litIsTrivial lit   -- Note [Floating literals]
     go (Tick t e) n  = not (tickishIsCode t) && go e n
     go (Cast e _)  n = go e n
     go (App e arg) n
        | Type {}     <- arg = go e n
        | Coercion {} <- arg = go e n
        | App (Var v) Type {} <- e      -- added clause
        , v `hasKey` noinlineIdKey
        , is_triv arg        = True
        | n==0               = False
        | is_triv arg        = go e (n-1)
        | otherwise          = False
 }}}

 `interestingDict` might need a similar treatment too.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16039#comment:4>
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