[GHC] #9136: Constant folding in Core could be better

[GHC]

#9136: Constant folding in Core could be better
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        Reporter:  simonpj                  |            Owner:  nomeata
            Type:  bug                      |           Status:  patch
        Priority:  normal                   |        Milestone:
       Component:  Compiler                 |          Version:  7.8.2
      Resolution:                           |         Keywords:
Operating System:  Unknown/Multiple         |     Architecture:
 Type of failure:  Runtime performance bug  |  Unknown/Multiple
       Test Case:                           |       Difficulty:  Unknown
        Blocking:                           |       Blocked By:
                                            |  Related Tickets:
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Changes (by nomeata):

 * status:  new => patch


Comment:

 Nofib shows that this optimization yields no measurable gain – most likely
 because later stages (maybe gcc) perform them anyways. So do we still want
 it, for the sake of pleasing Core, and maybe for the benefit of other
 backends like GHCJS?

 If yes, this can go in, so marking this as ready for review.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9136#comment:11>
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