[GHC] #12357: Increasing maximum constraint tuple size significantly blows up compiler allocations

[GHC]

#12357: Increasing maximum constraint tuple size significantly blows up compiler
allocations
-------------------------------------+-------------------------------------
        Reporter:  bgamari           |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.10.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by Ben Gamari <ben@…>):

 In [changeset:"eb3d6595735671605c5d6294a796dc0f16f784a4/ghc"
 eb3d6595/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="eb3d6595735671605c5d6294a796dc0f16f784a4"
 OccName: Avoid re-encoding derived OccNames

 Previously we would form derived OccNames by first decoding the name
 being derived from, manipulating it in [Char] form, and then
 re-encoding. This is all very wasteful as we essentially always just
 want to concatenate. Instead we now take care to form the final name
 with only one concatFS.

 Test Plan: Validate, examing compiler allocations

 Reviewers: simonpj, austin

 Reviewed By: simonpj

 Subscribers: thomie

 Differential Revision: https://phabricator.haskell.org/D2387

 GHC Trac Issues: #12357
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12357#comment:16>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler