[GHC] #13001: EnumFromThenTo is is not a good producer

[GHC]

#13001: EnumFromThenTo is is not a good producer
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        Reporter:  George            |                Owner:
            Type:  bug               |               Status:  new
        Priority:  low               |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  MacOS X           |         Architecture:  x86_64
 Type of failure:  Runtime           |  (amd64)
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by akio):

 I tested a [https://github.com/takano-
 akio/ghc/commit/930d42755e6753ba695157b96b8d651263b1934c a patch] and
 indeed marking `*FB` functions `INLINE[0]` seems to help.

 However this change increases binary sizes of some programs in nofib:

 {{{
 --------------------------------------------------------------------------------
         Program           Size    Allocs   Runtime   Elapsed  TotalMem
 --------------------------------------------------------------------------------
     gen_regexps          -0.3%      0.0%     0.000     0.000      0.0%
          puzzle          +0.8%      0.0%     0.089     0.090      0.0%
         reptile          +0.8%     -0.0%     0.008     0.008      0.0%
 --------------------------------------------------------------------------------
             Min          -0.3%     -0.0%     -7.3%     -7.1%      0.0%
             Max          +0.8%     +0.0%     +7.8%     +7.7%     +1.8%
  Geometric Mean          +0.0%     -0.0%     +0.2%     +0.2%     +0.0%
 }}}

 I have only looked at the code for `puzzle` so far. The increase in the
 code size seems to come from inlining `efdtInt*FB` into a derived `Enum`
 instance declaration.

 I wonder if this change is acceptable.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13001#comment:2>
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