[GHC] #9646: Simplifer non-determinism leading to 8 fold difference in run time performance

[GHC]

#9646: Simplifer non-determinism leading to 8 fold difference in run time
performance
-------------------------------------+-------------------------------------
              Reporter:  erikd       |            Owner:
                  Type:  bug         |           Status:  closed
              Priority:  normal      |        Milestone:  7.10.1
             Component:  Compiler    |          Version:  7.8.3
            Resolution:  fixed       |         Keywords:
      Operating System:  Linux       |     Architecture:  x86_64 (amd64)
       Type of failure:  Runtime     |       Difficulty:  Unknown
  performance bug                    |       Blocked By:
             Test Case:              |  Related Tickets:
              Blocking:              |
Differential Revisions:              |
-------------------------------------+-------------------------------------
Changes (by thomie):

 * status:  new => closed
 * resolution:   => fixed
 * milestone:   => 7.10.1


Comment:

 I just ran `make` in a clone of the testrepo from comment:12, after
 installing `primitive-0.5.4` in a cabal sandbox.

 Results with GHC 7.8.3:
 {{{
     Fast version etas : 0
     Slow version etas : 18
 }}}
 Results with GHC 7.9.20141108:
 {{{
     Fast version etas : 0
     Slow version etas : 0
 }}}
 So this bug must have been fixed somewhere along the way, although I don't
 know in which commit. Feel free to reopen if you think this answer is
 unsatisfactory, or hang tight till the 7.10 release.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9646#comment:13>
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