[GHC] #14941: Switching direct type family application to EqPred (~) prevents inlining in code using vector (10x slowdown)

[GHC]

#14941: Switching direct type family application to EqPred (~) prevents inlining in
code using vector (10x slowdown)
-------------------------------------+-------------------------------------
        Reporter:  nh2               |                Owner:  davide
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.2.2
      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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Changes (by davide):

 * Attachment "simple_case.zip" added.

 Simple case and benchmark.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14941>
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