[GHC] #5615: ghc produces poor code for `div` with constant powers of 2.

[GHC]

#5615: ghc produces poor code for `div` with constant powers of 2.
-------------------------------------+-------------------------------------
        Reporter:  Lennart           |                Owner:
                                     |  daniel.is.fischer
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.4.1-rc1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:  x86
 Type of failure:  Runtime           |            Test Case:
  performance bug                    |
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------
Changes (by akio):

 * cc: akio (added)


Comment:

 Am I right that for `div` and `mod` this is just waiting to be implemented
 (in PrelRules)?

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5615#comment:28>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler