[GHC] #7460: Double literals generated bad core

[GHC]

#7460: Double literals generated bad core
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    Reporter:  tibbe             |       Owner:                         
        Type:  bug               |      Status:  new                    
    Priority:  normal            |   Milestone:                         
   Component:  Compiler          |     Version:  7.4.2                  
    Keywords:                    |          Os:  Unknown/Multiple       
Architecture:  Unknown/Multiple  |     Failure:  Runtime performance bug
  Difficulty:  Unknown           |    Testcase:                         
   Blockedby:                    |    Blocking:                         
     Related:                    |  
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Changes (by daniel.is.fischer):

 * cc: daniel.is.fischer@… (added)


Comment:

 While we have no real `word2Double#`, would

 {{{
 {-# RULES
 "fromIntegral/Word->Double" fromIntegral = word2Double
   #-}

 correction :: Double
 correction = 2 * int2Double minBound

 word2Double :: Word -> Double
 word2Double w = case fromIntegral w of
                     i | i < 0 -> int2Double i - correction
                       | otherwise -> int2Double i
 }}}

 (and similar for `Float`) be an acceptable stand-in?

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7460#comment:4>
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