[GHC] #9203: Perf regression in 7.8.2 relative to 7.6.3, possibly related to HashMap

[GHC]

#9203: Perf regression in 7.8.2 relative to 7.6.3, possibly related to HashMap
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        Reporter:  simonmar                 |            Owner:
            Type:  bug                      |           Status:  merge
        Priority:  high                     |        Milestone:  7.8.3
       Component:  Compiler                 |          Version:  7.8.2
      Resolution:                           |         Keywords:
Operating System:  Unknown/Multiple         |     Architecture:
 Type of failure:  Runtime performance bug  |  Unknown/Multiple
       Test Case:                           |       Difficulty:  Unknown
        Blocking:                           |       Blocked By:
                                            |  Related Tickets:
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Comment (by Iavor S. Diatchki <diatchki@…>):

 In [changeset:"836981c7dec5c794ca94408468535cc018dc2e82/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="836981c7dec5c794ca94408468535cc018dc2e82"
 Redo instance to be more efficient (see #8778, #9203)
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9203#comment:10>
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