[GHC] #12368: Demand Analyzer: Cunnig plan not adhered to with aborting fixpoint interation

[GHC]

#12368: Demand Analyzer: Cunnig plan not adhered to with aborting fixpoint
interation
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        Reporter:  nomeata           |                Owner:
            Type:  bug               |               Status:  patch
        Priority:  low               |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D2392
       Wiki Page:                    |
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Comment (by nomeata):

 Working on this right now. I refactored the code quite a bit, removed some
 redundancies (such as passing around an strictness signature right next to
 an id, when that id is guaranteed to have been annotated with that
 strictness signature).

 Code pushed to `wip/12368`, push to Phabricator will happens once the
 automatic validators have validated the change.

 >  I think there is no need to do addPessimisticSigs.

 Are you sure? Any variable with useful information (strict or used-once)
 will not be included in `lazy_fv` (according to `splitFVs`). If we now
 also remove them from the strictness signatures, their uses are not
 recorded anywhere – and then probably considered absent. I’ll try to
 produce a test case to verify that theory.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12368#comment:12>
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