[GHC] #11195: New pattern-match check can be non-performant

[GHC]

#11195: New pattern-match check can be non-performant
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        Reporter:  goldfire          |                Owner:
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:
       Component:  Compiler          |              Version:  7.11
      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 bgamari):

 Looking at the code I'd suspect the problem is either `opt_trans_rule` or
 `opt_co4` as these both have a substantial number of patterns each with
 many guards. I'll try distilling a testcase from one of these.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11195#comment:1>
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