[GHC] #14338: Simplifier fails with "Simplifier ticks exhausted"

[GHC]

#14338: Simplifier fails with "Simplifier ticks exhausted"
-------------------------------------+-------------------------------------
        Reporter:  dredozubov        |                Owner:  bgamari
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.4.1
       Component:  Compiler          |              Version:  8.2.1
      Resolution:                    |             Keywords:
Operating System:  Linux             |         Architecture:  x86_64
 Type of failure:  Compile-time      |  (amd64)
  crash or panic                     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by bgamari):

 Indeed essentially all of this bloat comes from specialisations of the
 `HModify` and `HGet` dictionaries (see `Data.HSet` included in the
 testcase). For instance, we have,
 {{{#!hs
 -- RHS size: {terms: 5, types: 52, coercions: 426, joins: 0/0}
 $dHModify
   :: Data.HSet.HModify
        '[Payload 3, Payload 4, Payload 5, Payload 6, PayloadX]
        '[Payload 3, Payload 4, Payload 5, Payload 6, PayloadX]
        PayloadX
        PayloadX
        ('TypeFun.Data.Peano.S
           ('TypeFun.Data.Peano.S
              ('TypeFun.Data.Peano.S
                 ('TypeFun.Data.Peano.S 'TypeFun.Data.Peano.Z))))
 }}}
 It looks like we end up producing O(N) of these things, with each having
 O(N) (perhaps more?) coercions.

 I have added this ticket to the list of "coercion pile-up" issues on
 Performance/Compiler, since it seems pretty clear that this ticket falls
 in this bucket.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14338#comment:18>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler