[GHC] #12982: Missed constant folding oportunities

[GHC]

#12982: Missed constant folding oportunities
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        Reporter:  erikd             |                Owner:
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:  8.4.1
       Component:  libraries/hoopl   |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by sio):

 > Would anyone like to fix that? (Need to be careful to preserve overflow
 behaviour.)

 I'd like to take a crack at this. It'll be my first change, so will take
 me a while to get familiar with the codebase; will update when I've made
 some progress.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12982#comment:2>
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