[GHC] #8855: LLVM backend needs to use `-globalopt` explicitly

[GHC]

#8855: LLVM backend needs to use `-globalopt` explicitly
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       Reporter:  bgamari           |             Owner:
           Type:  bug               |            Status:  new
       Priority:  normal            |         Milestone:  7.8.1
      Component:  Compiler          |           Version:  7.8.1-rc1
       Keywords:                    |  Operating System:  Unknown/Multiple
   Architecture:  Unknown/Multiple  |   Type of failure:  None/Unknown
     Difficulty:  Unknown           |         Test Case:
     Blocked By:                    |          Blocking:
Related Tickets:                    |
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 While `-O1` and `-O2` includes a `-globalopt` pass, for reasons I don't
 entirely understand the location of the pass is such that not all aliases
 are eliminated. My `ghc-7.8` branch includes a patch fixing this (as well
 as removing ARM from the dynamic linking blacklist)[1].

 [1] https://github.com/bgamari/ghc/commits/ghc-7.8

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8855>
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