[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 Joachim Breitner <mail@…>):

 In [changeset:"8d92b88df7c1c04606c8a9e12c1d4bee65c990e4/ghc" 8d92b88/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="8d92b88df7c1c04606c8a9e12c1d4bee65c990e4"
 DmdAnal: Add a final, safe iteration

 this fixes #12368.

 It also refactors dmdFix a bit, removes 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).

 Note that when fixed-point iteration does not terminate, we
 conservatively delete their strictness signatures (set them to nopSig).
 But this loses the information on how its strict free variables are
 used!

 Lazily used variables already escape via lazy_fvs. We ensure that in the
 case of an aborted fixed-point iteration, also the strict variables are
 put there (with a conservative demand of topDmd).

 Differential Revision: https://phabricator.haskell.org/D2392
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12368#comment:16>
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