[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:"34ec0bd942b732b127b1a955cd3508da0a588b6f/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="34ec0bd942b732b127b1a955cd3508da0a588b6f"
 Rewrite coercionRole. (#9233)

 Summary:
 coercionRole is now much more efficient, computing both the coercion's
 kind and role together. The previous version calculated them separately,
 leading to quite possibly exponential behavior.

 This is still too slow, but it's a big improvement.

 Test Plan: Evaluate by running the "minimized" test from the Trac ticket.

 Reviewers: simonpj, austin

 Subscribers: simonmar, relrod, carter

 Differential Revision: https://phabricator.haskell.org/D73
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9233#comment:16>
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