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

GHC ghc-devs at haskell.org
Fri Jan 12 08:24:20 UTC 2018


#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:  8.4.1
       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:                    |
-------------------------------------+-------------------------------------

Comment (by tdammers):

 Right, didn't think to try without the `w-` and the `-2`. On my setup,
 there's no `next` in `Text/Regex/TDFA/NewDFA`, but four similar modules
 underneath it (`Engine`, `Engine_FA`, `Engine_NC`, and `Engine_NC_FA`) do
 have such a function defined in a let binding. It seems that the `Lazy`
 module ends up using the one in `Engine` (without any suffix), via
 `execMatch`.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14519#comment:18>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler


More information about the ghc-tickets mailing list