[GHC] #9203: Perf regression in 7.8.2 relative to 7.6.3, possibly related to Typeable

[GHC]

#9203: Perf regression in 7.8.2 relative to 7.6.3, possibly related to Typeable
------------------------------+--------------------------------------------
       Reporter:  simonmar    |             Owner:
           Type:  bug         |            Status:  new
       Priority:  normal      |         Milestone:  7.8.3
      Component:  Compiler    |           Version:  7.8.2
       Keywords:              |  Operating System:  Unknown/Multiple
   Architecture:              |   Type of failure:  Runtime performance bug
  Unknown/Multiple            |         Test Case:
     Difficulty:  Unknown     |          Blocking:
     Blocked By:              |
Related Tickets:              |
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 {{{
 $ git clone http://github.com/facebook/Haxl.git
 Cloning into 'Haxl'...
 remote: Counting objects: 77, done.
 remote: Compressing objects: 100% (65/65), done.
 remote: Total 77 (delta 17), reused 69 (delta 9)
 Unpacking objects: 100% (77/77), done.
 $ cd Haxl
 $ ghc-7.6.3 -O2 tests/Bench.hs -main-is Bench -o tests/Bench-76
 [1 of 6] Compiling Haxl.Core.StateStore ( Haxl/Core/StateStore.hs,
 Haxl/Core/StateStore.o )
 [2 of 6] Compiling Haxl.Core.Show1  ( Haxl/Core/Show1.hs,
 Haxl/Core/Show1.o )
 [3 of 6] Compiling Haxl.Core.Util   ( Haxl/Core/Util.hs, Haxl/Core/Util.o
 )
 [4 of 6] Compiling Haxl.Core.Types  ( Haxl/Core/Types.hs,
 Haxl/Core/Types.o )
 [5 of 6] Compiling Haxl.Core.DataCache ( Haxl/Core/DataCache.hs,
 Haxl/Core/DataCache.o )
 [6 of 6] Compiling Bench            ( tests/Bench.hs, tests/Bench.o )
 Linking tests/Bench-76 ...
 $ ./tests/Bench-76 500000
 Just (Right 0)
 insert: 0.87s
 500000
 lookup: 0.24s
 $ ./tests/Bench-76 500000
 Just (Right 0)
 insert: 0.87s
 500000
 lookup: 0.26s
 $ ghc-7.8.2 -O2 tests/Bench.hs -main-is Bench -o tests/Bench-78
 [1 of 5] Compiling Haxl.Core.StateStore ( Haxl/Core/StateStore.hs,
 Haxl/Core/StateStore.o )
 [2 of 5] Compiling Haxl.Core.Show1  ( Haxl/Core/Show1.hs,
 Haxl/Core/Show1.o )
 [3 of 5] Compiling Haxl.Core.Types  ( Haxl/Core/Types.hs,
 Haxl/Core/Types.o )
 [4 of 5] Compiling Haxl.Core.DataCache ( Haxl/Core/DataCache.hs,
 Haxl/Core/DataCache.o )
 [5 of 5] Compiling Bench            ( tests/Bench.hs, tests/Bench.o )
 Linking tests/Bench-78 ...
 $ ./tests/Bench-78 500000
 Just (Right 0)
 insert: 1.09s
 500000
 lookup: 0.44s
 $ ./tests/Bench-78 500000
 Just (Right 0)
 insert: 1.08s
 500000
 lookup: 0.44s
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9203>
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