[GHC] #14287: Early inlining causes potential join points to be missed

[GHC]

#14287: Early inlining causes potential join points to be missed
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        Reporter:  jheek             |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.2.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by mpickering):

 Another way to make the program faster is to write

 {{{
 sfilter3 :: (a -> Bool) -> Stream s a -> Stream s a
 sfilter3 pred (Stream step s0) = Stream filterStep s0 where
   filterStep s =
     let go s =
           case step s of
             Done -> Done
             Yield x ns
               | pred x    -> Yield x ns
               | otherwise -> go ns
     in go s
 }}}

 or to perform the transformation described by Simon in #13966.

 Both leads to precisely the same core as the `INLINE [2]` version.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14287#comment:3>
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