[GHC] #14614: Compile time regression when compiling alex generated files

[GHC]

#14614: Compile time regression when compiling alex generated files
-------------------------------------+-------------------------------------
           Reporter:  AndreasK       |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.2.2
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:  #11380
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 Compile time increased slightly from 7.10.3 to 8.0.2 and significantly
 when going to 8.2.2

 {{{
 compiler=ghc-7.10.3

 /c/test/happy-example
 $ time ghc Tokens.hs -fforce-recomp -fno-code
 [1 of 1] Compiling Tokens           ( Tokens.hs, nothing )

 real    0m0.243s




 compiler=ghc-8.0.2

 /c/test/happy-example
 $ time ghc Tokens.hs -fforce-recomp -fno-code
 [1 of 1] Compiling Tokens           ( Tokens.hs, nothing )

 real    0m0.286s




 compiler=ghc-8.2.2

 $ time ghc Tokens.hs -fforce-recomp -fno-code
 [1 of 1] Compiling Tokens           ( Tokens.hs, nothing )

 real    0m0.721s
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14614>
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