[GHC] #12545: Compilation time/space regression in GHC 8.0/8.1 (search in type-level lists and -O)

[GHC]

#12545: Compilation time/space regression in GHC 8.0/8.1 (search in type-level
lists and -O)
-------------------------------------+-------------------------------------
        Reporter:                    |                Owner:  (none)
  mikhail.vorozhtsov                 |
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:  Inlining
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 Incidentally, HEAD is much much better:
 {{{
 7.10   19.2G allocated by GHC
        50 seconds

 HEAD    7.1G allocated by GHC
         30 seconds
 }}}
 I gave up waiting for 8.0.   So apparently the original problem has gone
 away, although I'd quite like to know how!

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12545#comment:13>
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