#4227: Allow SPECIALISE pragmas for functions defined in another module
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Reporter: simonpj | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 6.12.3
Keywords: | Difficulty:
Os: Unknown/Multiple | Testcase:
Architecture: Unknown/Multiple | Failure: None/Unknown
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See http://www.haskell.org/pipermail/glasgow-haskell-
users/2010-July/019042.html
{{{
say I have
module A where
class C a where ...
f :: C a => String -> a
module B where
import A
data T = ...
instance C T where ...
g :: String -> SomeOtherType
g s = doSomethingWith (f s)
}}}
Is it possible to SPECIALIZE `f` for the type `T`? Currently no.
Some care would be needed to support this. Currently GHC's `-fexpose-all-
unfoldings` makes no attempt to ensure that the exposed unfolding for f is
exactly what the user originally wrote. For example, other functions
might have been inlined into f's RHS that might make it a lot bigger.
Maybe you'd want to say
{{{
{-# SPECIALISABLE f #-}
f = <blah>
}}}
to mean "expose f's unfolding, pretty much as-is, rather than optimising
it". This is close to what you get with
{{{
{-# INLINE f #-}
}}}
(which also exposes the original RHS) but without the "please inline me at
every call site" meaning.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4227>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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