[GHC] #14254: The Binary instance for TypeRep smells a bit expensive

[GHC]

#14254: The Binary instance for TypeRep smells a bit expensive
-------------------------------------+-------------------------------------
        Reporter:  dfeuer            |                Owner:  (none)
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:  8.4.1
       Component:  Compiler          |              Version:  8.2.1
      Resolution:                    |             Keywords:  Typeable
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:D3998,
       Wiki Page:                    |  Phab:D4078, Phab:D4082
-------------------------------------+-------------------------------------

Comment (by simonpj):

 > to avoid these performance problems

 I would love to know what "these performance problems" actually are. The
 ticket description is opaque to me.   Can someone offer a program that
 behaves badly, and an explanation of what is bad?  It's hard for me to
 review a patch without knowing the problem that it seeks to solve.

 comment:9 offers two patches.  Are they alternatives?  Or do we need them
 both? Do they solve two different problems?  What are those two problems.

 Finally, does this all have something to do with #14337?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14254#comment:10>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler