#9509: No automatic specialization of inlinable imports in 7.8
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Reporter: dolio | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 7.8.3
Keywords: | Operating System:
Architecture: Unknown/Multiple | Unknown/Multiple
Difficulty: Unknown | Type of failure: Runtime
Blocked By: | performance bug
Related Tickets: | Test Case:
| Blocking:
| Differential Revisions:
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According to the GHC manual, any uses of an imported definition that is
overloaded and INLINABLE will automatically cause a SPECIALIZE to be
generated for those uses, if appropriate. However, this no longer appears
to be the case in 7.8(.3). Here is a simple test case:
{{{#!hs
module A (foo) where
import Data.IORef
foo :: Ord a => a -> IO a
foo x = newIORef x >>= readIORef >>= \y -> case compare x y of LT ->
return x ; _ -> return y
{-# INLINABLE foo #-}
}}}
{{{#!hs
module Main (main) where
import A
main = foo (5 :: Int) >>= print
}}}
`foo` is constructed to be long enough that GHC 7.8.3 will elect to not
inline it.
When compiling with 7.6.3, the core contains the following:
{{{
Main.$sfoo1
:: GHC.Types.Int
-> GHC.Prim.State# GHC.Prim.RealWorld
-> (# GHC.Prim.State# GHC.Prim.RealWorld, GHC.Types.Int #)
[GblId,
Arity=2,
Caf=NoCafRefs,
Str=DmdType LL,
Unf=Unf{Src=<vanilla>, TopLvl=True, Arity=2, Value=True,
ConLike=True, WorkFree=True, Expandable=True,
Guidance=IF_ARGS [20 0] 55 30}]
Main.$sfoo1 =
\ (x_XkE :: GHC.Types.Int)
(eta_B1 :: GHC.Prim.State# GHC.Prim.RealWorld) ->
case GHC.Prim.newMutVar#
@ GHC.Types.Int @ GHC.Prim.RealWorld x_XkE eta_B1
of _ { (# ipv_amT, ipv1_amU #) ->
case GHC.Prim.readMutVar#
@ GHC.Prim.RealWorld @ GHC.Types.Int ipv1_amU ipv_amT
of ds1_amJ { (# ipv2_Xn8, ipv3_Xna #) ->
case x_XkE of wild_axu { GHC.Types.I# x#_axw ->
case ipv3_Xna of _ { GHC.Types.I# y#_axA ->
case GHC.Prim.<# x#_axw y#_axA of _ {
GHC.Types.False -> ds1_amJ;
GHC.Types.True -> (# ipv2_Xn8, wild_axu #)
}
}
}
}
}
Main.$sfoo :: GHC.Types.Int -> GHC.Types.IO GHC.Types.Int
[GblId,
Arity=2,
Caf=NoCafRefs,
Str=DmdType LL,
Unf=Unf{Src=<vanilla>, TopLvl=True, Arity=0, Value=True,
ConLike=True, WorkFree=True, Expandable=True,
Guidance=ALWAYS_IF(unsat_ok=True,boring_ok=True)}]
Main.$sfoo =
Main.$sfoo1
`cast` (