[GHC] #8949: switch -msse2 to be on by default

[GHC]

#8949: switch -msse2 to be on by default
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        Reporter:  errge             |            Owner:
            Type:  bug               |           Status:  new
        Priority:  normal            |        Milestone:
       Component:  Compiler          |          Version:  7.9
  (CodeGen)                          |         Keywords:
      Resolution:                    |     Architecture:  x86
Operating System:  Unknown/Multiple  |       Difficulty:  Moderate (less
 Type of failure:  Other             |  than a day)
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
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Comment (by simonmar):

 Replying to [comment:2 tibbe]:
 > I think we should, like LLVM, switch on -march=native by default and
 have people who want to build more portable binaries specify their target
 explicitly. This doesn't preclude turning on -msse2 by default of course.

 I like `-march-native`, but I'm not convinced it should be the default.
 For GHC it will add minimal gain, in exchange for some very obscure
 crashes when someone forgets to turn it off when building a binary that
 might need to run on another machine.  The Haskell way is correct but slow
 by default, and I think that's what we should do here.

 I think I'm less concerned about `-msse2`, because it will affect a lot
 fewer people.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8949#comment:5>
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