[GHC] #10397: Compiler performance regression 7.6 -> 7.8 in elimCommonBlocks

[GHC]

#10397: Compiler performance regression 7.6 -> 7.8 in elimCommonBlocks
-------------------------------------+-------------------------------------
        Reporter:  TobyGoodwin       |                   Owner:
            Type:  bug               |                  Status:  patch
        Priority:  normal            |               Milestone:
       Component:  Compiler          |                 Version:  7.8.4
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |  performance
 Type of failure:  None/Unknown      |            Architecture:
      Blocked By:                    |  Unknown/Multiple
 Related Tickets:                    |               Test Case:  see ticket
                                     |                Blocking:
                                     |  Differential Revisions:  Phab:D892
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Comment (by Joachim Breitner <mail@…>):

 In [changeset:"c256357242ee2dd282fd0516260edccbb7617244/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="c256357242ee2dd282fd0516260edccbb7617244"
 Speed up elimCommonBlocks by grouping blocks also by outgoing labels

 This is an attempt to improve the situation described in #10397, where
 the linear scan of possible candidates for commoning up is far too
 expensive. There is (ever) more room for improvement, but this is a
 start.

 Differential Revision: https://phabricator.haskell.org/D892
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10397#comment:17>
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