[GHC] #14644: Improve cmm/assembly for pattern matches with two constants.

[GHC]

#14644: Improve cmm/assembly for pattern matches with two constants.
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        Reporter:  AndreasK          |                Owner:  (none)
            Type:  task              |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.2.2
  (CodeGen)                          |             Keywords:  Codegen, CMM,
      Resolution:                    |  Patterns, Pattern Matching
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 AndreasK):

 It should also be possible to see the difference using criterion or
 instruction counters when running affected code in a tight loop.

 I will take a stab at changing the logic to `if ... else if ... else` for
 these cases. I think that's a good starting point to learn how Cmm works
 inside GHC.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14644#comment:2>
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