[GHC] #12150: Compile time performance degradation on code that uses undefined/error with CallStacks

[GHC]

#12150: Compile time performance degradation on code that uses undefined/error with
CallStacks
-------------------------------------+-------------------------------------
        Reporter:  thomie            |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.2.2
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #10844            |  Differential Rev(s):  Phab:D3753
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by dfeuer):

 What we're doing here smells an awful lot like what we're doing in the
 case-of-known-constructor transformation in `rebuildCase`. Rather than a
 known constructor, we're dealing with a known bottom. Would it make sense
 to move the bottom check there, or is that nonsense? I don't have a great
 sense of how all these pieces fit together yet.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12150#comment:21>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler