#2271: floor, ceiling, round :: Double -> Int are awesomely slow
------------------------------------------+---------------------------------
Reporter: dons | Owner: daniel.is.fischer
Type: bug | Status: new
Priority: low | Milestone: 7.0.1
Component: libraries/base | Version: 7.1
Keywords: performance, math, double | Testcase:
Blockedby: | Difficulty: Unknown
Os: Unknown/Multiple | Blocking:
Architecture: Unknown/Multiple | Failure: None/Unknown
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Changes (by daniel.is.fischer):
* version: 6.8.2 => 7.1
Comment:
I'm almost on the verge of giving up. I have the code, the code works and
is faster than the old code, but I cannot get the rewrite rules to fire.
When I compile some code, for example
{{{
main :: IO ()
main = print (properFraction (encodeFloat (2^23) 16 :: Float) :: (Int,
Float))
}}}
-ddump-rule-firings says
{{{
Rule fired: SPEC GHC.Real.^
Rule fired: Class op encodeFloat
Rule fired: Class op properFraction
Rule fired: SPEC $cproperFraction [GHC.Types.Int]
Rule fired: Class op show
Rule fired: <#
Rule fired: Class op showsPrec
Rule fired: Class op showsPrec
}}}
instead of the desired
{{{
Rule fired: properFraction/Float->Int
}}}
Note that there's no SPECIALISE nor INLINE pragma anywhere concerning the
!RealFrac instance.
What's going on?
I'm currently building with explicit NOINLINE pragmas, if that doesn't
help, I'm lost.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2271#comment:15>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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