[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):  Phab:D2400
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by simonpj):

 This all dates from when tuples were not in the original name cache (and I
 think they should indeed not be).  But we made a special case for the unit
 tuple; I forget why, and it probably doesn't matter much.

 No, we must initialise the cache will all known-key tycons (tuples aside)
 otherwise, well, we won't assign the right known key to one of them.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12357#comment:25>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler