[GHC] #13570: CoreFVs patch makes n-body slower

[GHC]

#13570: CoreFVs patch makes n-body slower
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        Reporter:  simonpj           |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            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):
       Wiki Page:                    |
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Comment (by dfeuer):

 Whatever's going on here looks really subtle. The simplifier dumps appear
 to be exactly the same, except for doing things in slighly different
 orders. The STG dumps are a bit harder to read, but the difference in CMM
 dumps is sufficiently small and confined that someone familiar with CMM
 might well be able to see what's going on there directly. I'll have to
 learn something about that pretty soon, I imagine, but I don't know it
 yet.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13570#comment:2>
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