id,summary,reporter,owner,description,type,status,priority,milestone,component,version,resolution,keywords,cc,os,architecture,failure,difficulty,testcase,blockedby,blocking,related
5731,Bad code for Double literals,rl,igloo,"Caught by the `vector` benchmark suite. Small program:

{{{
foo :: [Double] -> [Double]
foo = map f
  where
    f x = 1 / x
}}}

The current head generates this rather terrible code (with -O2):

{{{
foo3 :: GHC.Integer.Type.Integer
foo3 = __integer 1

foo2 :: GHC.Types.Double
foo2 =
  case GHC.Integer.Type.doubleFromInteger foo3
  of wild_afu { __DEFAULT ->
  GHC.Types.D# wild_afu
  }

foo1 :: GHC.Types.Double -> GHC.Types.Double
foo1 =
  \ (eta_B1 :: GHC.Types.Double) ->
    GHC.Float.divideDouble foo2 eta_B1

foo :: [GHC.Types.Double] -> [GHC.Types.Double]
foo = GHC.Base.map @ GHC.Types.Double @ GHC.Types.Double foo1
}}}

It does generate perfectly fine code for this, though:

{{{
bar :: [Double] -> [Double]
bar = map (\x -> 1/x)
}}}",bug,closed,highest,7.4.1,Compiler,7.3,fixed,,,Unknown/Multiple,Unknown/Multiple,Runtime performance bug,Unknown,,,,