[GHC] #8082: Ordering of assembly blocks affects performance

[GHC]

#8082: Ordering of assembly blocks affects performance
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        Reporter:  jstolarek         |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Compiler (NCG)    |                 Version:  7.6.3
      Resolution:                    |                Keywords:
Operating System:  Linux             |            Architecture:  x86_64
 Type of failure:  Runtime           |  (amd64)
  performance bug                    |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
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Comment (by nomeata):

 I can confirm that this can cause serious wobbles. When working on #10137,
 I changed the use of `<` to `>=` when generating if-then-else trees, and
 some numbers went up and some went down, without any guidance as to which
 one is better:
 {{{
            Min          -0.1%     -0.0%     -3.2%     -3.2%      0.0%
            Max          +0.0%      0.0%     +4.4%     +4.3%     +3.3%
 Geometric Mean          -0.0%     -0.0%     +0.3%     +0.3%     +0.1%
 }}}

 Looks like without dynamic tracing, this problem is not easily solved.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8082#comment:4>
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