[GHC] #10007: Fix misattribution of Cost Centre profiles to lintAnnots

[GHC]

#10007: Fix misattribution of Cost Centre profiles to lintAnnots
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        Reporter:  thoughtpolice     |                   Owner:  scpmw
            Type:  bug               |                  Status:  merge
        Priority:  high              |               Milestone:  7.10.1
       Component:  Profiling         |                 Version:  7.10.1-rc1
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  Incorrect result  |  Unknown/Multiple
  at runtime                         |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:  #9961             |  Differential Revisions:  Phab:D616
                                     |  Phab:D636
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Comment (by scpmw):

 Well, it's the wrong fix, as far as I'm concerned. Yes, it fixes the
 erroneous attribution to `lintAnnots`, but only because we change the
 program's (RTS) cost semantics twice during optimisations, with both
 instances un-doing each other. This is not guaranteed, see the new test
 case for `D616`.

 I also didn't feel it would help the discussion to mention this - but this
 also doesn't fix rather silly double-annotations on parameters, which (I
 think) only don't appear because we automatically eliminate repeating cost
 centres in stacks. If needed, I could produce another test case that
 demonstrates that.

 Short version: This is only a band-aid. And as far as those go, I would
 still prefer `D616`. At least until I have figured out how to *actually*
 implement `Eval2`, which would fix the whole situation from the RTS end.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10007#comment:4>
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