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

[GHC]

#16039: 'GHC.Magic.noinline <var>' should not float out
-------------------------------------+-------------------------------------
        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 simonpj):

 I think the underlying point is that you want `(noinline f)` to be treated
 very like `f`, for many purposes.  Because it'll turn ''into'' `f` in
 `CorePrep`.

 Particularly, I think you want `exprIsTrivial` to be true of it.  So maybe
 instead of
 {{{
 exprIsTrivial (App e arg)      = not (isRuntimeArg arg) && exprIsTrivial e
 }}}
 you want
 {{{
 exprIsTrivial (App e arg)
  | not (isRuntimeArg arg)
  = exprIsTrivial e
  | App (Var f) _ <- e, isInlineId f
  = exprIsTrivial arg
  | otherwise
  = False
 }}}
 Not very nice, and it's possible that other functions may need similar
 treatment.  But nothing better jumps out at me.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16039#comment:3>
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