[GHC] #13719: checkFamInstConsistency dominates compile time

[GHC]

#13719: checkFamInstConsistency dominates compile time
-------------------------------------+-------------------------------------
        Reporter:  niteria           |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  8.3
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #13092, #13099,   |  Differential Rev(s):  phab:D3600,
  #12191                             |  phab:D3602, phab:D3603
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by Bartosz Nitka <niteria@…>):

 In [changeset:"69d9081d9fa3ff36fda36e4e11ef7e8f946ecf2a/ghc"
 69d9081d/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="69d9081d9fa3ff36fda36e4e11ef7e8f946ecf2a"
 Faster checkFamInstConsistency

 This implements the idea from
 https://ghc.haskell.org/trac/ghc/ticket/13092#comment:14.

 It's explained in Note [Checking family instance optimization]
 in more detail.

 This improves the test case T13719 tenfold and
 cuts down the compile time on `:load` in `ghci` on our
 internal code base by half.

 Test Plan: ./validate

 Reviewers: simonpj, simonmar, rwbarton, austin, bgamari

 Reviewed By: simonpj

 Subscribers: thomie

 GHC Trac Issues: #13719

 Differential Revision: https://phabricator.haskell.org/D3603
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13719#comment:7>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler