[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
-------------------------------------+-------------------------------------
        Reporter:  ntc2              |                Owner:  tdammers
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.6.1
       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:                    |
-------------------------------------+-------------------------------------

Comment (by tdammers):

 > If not (and I bet it doesn't), then which modules must be compiled
 without -O to make the problem go away?

 Any quick hints on how to do that? Can I somehow instruct cabal to use
 specific GHC flags selectively for some modules?

 Setting `-O0` for the main module alone doesn't make the problem go away
 in any case, while setting `-O0` for the entire regex-tdfa-text package
 does. But that doesn't tell us much of course.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14519#comment:29>
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