[GHC] #10124: Simple case analyses generate too many branches

[GHC]

#10124: Simple case analyses generate too many branches
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        Reporter:  bgamari           |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Compiler          |                 Version:  7.8.4
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:  #6135             |  Differential Revisions:
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Comment (by bgamari):

 I would hope that the example above would get lowered to something like
 the following,

 {{{#!hs
 let !p = a ==# 1 `orI#` a ==# 5 `orI#` a ==# 8 `orI#` a ==# 9 `orI#` a ==#
 11 `orI#` a ==# 19
 case p of
   1 -> do_something
   0 -> do_something_else
 }}}

 The idea is that I'd want to avoid emitting branches in this case.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10124#comment:4>
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