[GHC] #15176: Superclass `Monad m =>` makes program run 100 times slower

[GHC]

#15176: Superclass `Monad m =>` makes program run 100 times slower
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        Reporter:  danilo2           |                Owner:  osa1
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:  8.8.1
       Component:  Compiler          |              Version:  8.4.2
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 When generating .ticky files I do this
 {{{
 ghc -O -ticky -dverbose-core2core -ddump-stg Foo.hs >& Foo.stg
 ./Foo +RTS -rFoo.ticky
 }}}
 The ticky files are utterly useless without the accompanying `-dverbose-
 core2core -ddump-stg` output, produced in the very same run of GHC.

 Would you like to do that and upload the results?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15176#comment:12>
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