[GHC] #9233: Compiler performance regression

[GHC]

#9233: Compiler performance regression
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              Reporter:  augustss    |             Owner:
                  Type:  bug         |            Status:  new
              Priority:  low         |         Milestone:
             Component:  Compiler    |           Version:  7.8.2
            Resolution:              |          Keywords:
Differential Revisions:  Phab:D73    |  Operating System:  Windows
          Architecture:              |   Type of failure:  None/Unknown
  Unknown/Multiple                   |         Test Case:
            Difficulty:  Unknown     |          Blocking:
            Blocked By:              |
       Related Tickets:              |
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Comment (by Richard Eisenberg <eir@…>):

 In [changeset:"5e7406d9f5857e4ff30aed348f731d16dbd8e64c/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="5e7406d9f5857e4ff30aed348f731d16dbd8e64c"
 Optimise optCoercion. (#9233)

 The old optCoercion (and helper functions) used coercionKind and
 coercionRole internally. This was terrible when these had to be
 called at *every* point in the coercion tree during the recursive
 descent. This is rewritten to avoid such calls.
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9233#comment:17>
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