[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:  AndreasK
            Type:  task              |               Status:  patch
        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):  Phab:D4294
       Wiki Page:                    |
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Comment (by AndreasK):

 Replying to [comment:9 simonpj]:
 > Didn't you say "I ran a simple Benchmark and the results seem almost too
 good with >10% gains in almost all cases.".  But now you say "mostly no
 change; one gets 5-9%".   Were the earlier measurements wrong?

 No these are right. But the simple benchmark was running the code I posted
 above in
 [https://ghc.haskell.org/trac/ghc/ticket/14644?replyto=9#comment:5 comment
 5]. All cases referred to the  pos/neg/.. branches in that case.

 Nofib seems to be in a permanent state of breakdown on windows so I
 stopped using it in my initial benchmarks.
 And it was the [https://ghc.haskell.org/trac/ghc/ticket/14656 right]
 [https://ghc.haskell.org/trac/ghc/ticket/14655 thing]
 [https://ghc.haskell.org/trac/ghc/ticket/14654 to do ] as it took some
 work to get it running.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14644#comment:10>
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