[GHC] #10528: compile time performance regression with OverloadedStrings and Text

[GHC]

#10528: compile time performance regression with OverloadedStrings and Text
-------------------------------------+-------------------------------------
        Reporter:  jakewheat         |                   Owner:  bgamari
            Type:  bug               |                  Status:  merge
        Priority:  high              |               Milestone:  7.10.3
       Component:  Compiler          |                 Version:  7.10.2-rc2
      Resolution:                    |                Keywords:
Operating System:  Linux             |            Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
-------------------------------------+-------------------------------------

Comment (by jakewheat):

 I wasn't able to see the speed up with the reduced test case code above
 either:

 ghc 7.10.2, text 1.2.1.1

 {{{
 time ghc Test.hs -c -fforce-recomp -Rghc-timing -O -package-db .cabal-
 sandbox/x86_64-linux-ghc-7.10.2-packages.conf.d/
 <<ghc: 2715366976 bytes, 544 GCs, 17352140/46388280 avg/max bytes
 residency (13 samples), 111M in use, 0.000 INIT (0.001 elapsed), 2.000 MUT
 (1.892 elapsed), 0.844 GC (1.033 elapsed) :ghc>>

 real    0m2.958s
 user    0m2.908s
 sys     0m0.048s
 }}}

 ghc 7.10.2, text 1.2.1.2

 {{{
 time ghc Test.hs -c -fforce-recomp -Rghc-timing -O -package-db .cabal-
 sandbox/x86_64-linux-ghc-7.10.2-packages.conf.d/
 <<ghc: 2725083744 bytes, 576 GCs, 16625100/31660992 avg/max bytes
 residency (14 samples), 87M in use, 0.000 INIT (0.001 elapsed), 1.948 MUT
 (1.885 elapsed), 0.876 GC (1.034 elapsed) :ghc>>

 real    0m2.954s
 user    0m2.892s
 sys     0m0.060s
 }}}

 ghc 7.10.1, text 1.2.1.2

 {{{
 time ghc Test.hs -c -fforce-recomp -Rghc-timing -O -package-db .cabal-
 sandbox/x86_64-linux-ghc-7.10.1-packages.conf.d/
 <<ghc: 184198016 bytes, 98 GCs, 5557874/16933408 avg/max bytes residency
 (7 samples), 36M in use, 0.000 INIT (0.001 elapsed), 0.140 MUT (0.120
 elapsed), 0.112 GC (0.138 elapsed) :ghc>>

 real    0m0.289s
 user    0m0.280s
 sys     0m0.004s
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10528#comment:21>
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