[GHC] #8279: bad alignment in code gen yields substantial perf issue

[GHC]

#8279: bad alignment in code gen  yields substantial perf issue
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        Reporter:  carter            |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.7
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #8082             |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by George):

 re Simon PJ's comment 17, would it be relatively easy to do this with the
 llvm compiler? AFAIK opt and llc don't seem to have the appropriate
 options but clang has -Os and -Oz (see
 [https://clang.llvm.org/docs/CommandGuide/clang.html]) so I would hope it
 wouldn't be too hard to do in the Haskell llvm compiler.

 Also wrt llvm there is mention of alignment here
 [http://llvm.org/docs/Frontend/PerformanceTips.html]. I'm sure most people
 interested in the llvm compiler are aware of this doc but I thought I may
 as well mention it to be complete.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8279#comment:26>
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