[GHC] #11822: Pattern match checker exceeded (2000000) iterations

[GHC]

#11822: Pattern match checker exceeded (2000000) iterations
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        Reporter:  j.waldmann        |                Owner:  gkaracha
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1-rc3
      Resolution:                    |             Keywords:
                                     |  PatternMatchWarnings
Operating System:  Unknown/Multiple  |         Architecture:  x86_64
 Type of failure:  Compile-time      |  (amd64)
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by niteria):

 Ok, it doesn't look like the asymptotics changed between `7.10.3` and
 `8.0`.
 Numbers from `7.10.3`:
 {{{
 $ for i in 1 10 100 1000 2000 4000 10000 20000; do echo $i; ./A.gen.sh $i
 > A.hs && (time ~/local/third-
 party2/ghc/7.10.3/gcc-4.9-glibc-2.20-fb/e0e26d4/bin/ghc -dno-debug-output
 A.hs) 2>&1 | grep real; done
 1
 real    0m0.126s
 10
 real    0m0.161s
 100
 real    0m0.207s
 1000
 real    0m1.428s
 2000
 real    0m3.875s
 4000
 real    0m11.783s
 10000
 real    1m13.631s
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11822#comment:19>
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