[GHC] #14519: Exponential runtime performance regression in GHC 8.2 + Data.Text.Lazy + Text.RE.TDFA

[GHC]

#14519: Exponential runtime performance regression in GHC 8.2 + Data.Text.Lazy +
Text.RE.TDFA
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        Reporter:  ntc2              |                Owner:  tdammers
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.4.1
       Component:  Compiler          |              Version:  8.2.2
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  Runtime           |            Test Case:
  performance bug                    |  https://github.com/ntc2/ghc-8.2.1
                                     |  -regex-lazy-text-
                                     |  bug/tree/07b7bb32c6e90e8f2d2eada4b59943f37e632d53
      Blocked By:                    |             Blocking:
 Related Tickets:  #13745, #14564    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by tdammers):

 I took a stab at bisecting this myself, the problem however is that I'm
 getting too many false positives, even when cleaning thoroughly and
 starting with as clean a slate as possible, and when I do that, build
 times become prohibitive, so I gave up after a few night-long attempts. So
 I will now take a different route, trying to isolate the problem further
 on current GHC HEAD, see if I can pin it down.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14519#comment:7>
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