[GHC] #10069: CPR related performance issue

[GHC]

#10069: CPR related performance issue
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        Reporter:  pacak             |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.10.1-rc2
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by Fuuzetsu):

 Data-point from 8.6.2 using original code (first comment):

 {{{
 [nix-shell:/tmp]$ ghc -O2 Blah.hs && ./Blah
 benchmarking single call/A
 time                 21.83 ns   (21.55 ns .. 22.09 ns)
                      0.999 R²   (0.999 R² .. 1.000 R²)
 mean                 21.77 ns   (21.62 ns .. 22.07 ns)
 std dev              705.5 ps   (434.8 ps .. 1.223 ns)
 variance introduced by outliers: 53% (severely inflated)

 benchmarking single call/B
 time                 9.741 ns   (9.581 ns .. 9.937 ns)
                      0.998 R²   (0.996 R² .. 0.999 R²)
 mean                 9.762 ns   (9.641 ns .. 9.942 ns)
 std dev              490.4 ps   (347.4 ps .. 649.6 ps)
 variance introduced by outliers: 74% (severely inflated)
 }}}

 I'm attaching -ddump-simpl output (Blah.dump-simpl). It seems the ticket
 is still a problem and not 3-5% but 100%

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10069#comment:26>
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