[GHC] #9961: compile-time performance regression compiling genprimcode

[GHC]

#9961: compile-time performance regression compiling genprimcode
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        Reporter:  hvr               |                   Owner:  simonpj
            Type:  bug               |                  Status:  new
        Priority:  normal            |               Milestone:  7.10.1
       Component:  Compiler          |                 Version:  7.10.1-rc1
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
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Comment (by hvr):

 That's weird... I just tried with today's GHC HEAD (at
 696f2cfdea4ab87cc457b141323bb25ab4afe795), and a `BuildFlavour="quick"`
 build. The exact steps I took now were:

 {{{#!sh
 cd utils/genprimopcode/

 rm *.o *.hi

 alex Lexer.x

 ../inplace/bin/ghc-stage2 -Rghc-timing -O -c ParserM.hs
 # <<ghc: 906859816 bytes, 319 GCs, 4611760/14141808 avg/max bytes
 residency (8 samples), 31M in use, 0.001 INIT (0.001 elapsed), 0.822 MUT
 (0.833 elapsed), 0.225 GC (0.225 elapsed) :ghc>>

 ../inplace/bin/ghc-stage2 -Rghc-timing -O -c Lexer.hs
 # ...runs for over 15 minutes...
 }}}

 So I can actually reproduce this with GHC HEAD

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9961#comment:5>
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