[GHC] #12962: No automatic SCC annotations for functions marked INLINABLE

[GHC]

#12962: No automatic SCC annotations for functions marked INLINABLE
-------------------------------------+-------------------------------------
        Reporter:  MikolajKonarski   |                Owner:  dfeuer
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.4.1
       Component:  Profiling         |              Version:  8.0.1
      Resolution:                    |             Keywords:  Inlining,
                                     |  newcomer
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #12963            |  Differential Rev(s):  Phab:D3550
       Wiki Page:                    |
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Comment (by dfeuer):

 Simon, there's a Note [inline sccs] about why we don't have them for
 `INLINE` things:

 {{{#!hs
 -- It should be reasonable to add ticks to INLINE functions; however
 -- currently this tickles a bug later on because the SCCfinal pass
 -- does not look inside unfoldings to find CostCentres.  It would be
 -- difficult to fix that, because SCCfinal currently works on STG and
 -- not Core (and since it also generates CostCentres for CAFs,
 -- changing this would be difficult too).
 --
 -- Another reason not to add ticks to INLINE functions is that this
 -- sometimes handy for avoiding adding a tick to a particular function
 -- (see #6131)
 --
 -- So for now we do not add any ticks to INLINE functions at all.
 }}}

 Even if dealing with ticks through inlining isn't feasible, this whole
 thing seems a bit surprising to me because `INLINE` bindings aren't always
 inlined, and non-`INLINE` bindings often are. Using an `INLINE` annotation
 for its side effect on SCC annotations seems rather ugly.

 The current proposed change just does what osa1 seems to suggest, limiting
 the exclusion to `INLINE` rather than to both `INLINE` and `INLINABLE` in
 `Coverage.hs`. This appears to affect ticks generally, rather than SCC
 ticks specifically, but that ''seems'' to my uneducated eye to be the case
 for the various auto-add options too (see `shouldTickBind` and
 `mkDensity`).

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12962#comment:18>
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