[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)
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        Reporter:                    |                Owner:
  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 goldfire):

 This, to me, does not look like a cut-and-dried type-level issue. Note
 that the number of ''terms'' is much greater in 8.0. And the ratio of
 coercions to terms is ''lower'' in 8.0 than 7.10.

 It looks like the occurrence analysis in 8.0 is to blame for the blowup in
 terms... whereas that same pass in 7.10 caused more of a blowup in
 coercions. Weird.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12545#comment:7>
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