#4945: Another SpecConstr infelicity
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Reporter: batterseapower | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 7.0.1 | Keywords:
Testcase: | Blockedby:
Os: Unknown/Multiple | Blocking:
Architecture: Unknown/Multiple | Failure: Runtime performance bug
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Comment(by batterseapower):
OK, I got it. All you need to do is replace varUsage with:
{{{
varUsage :: ScEnv -> OutVar -> ArgOcc -> ScUsage
varUsage env v use = case lookupHowBound env v of
Just RecArg -> SCU { scu_calls = emptyVarEnv
, scu_occs = unitVarEnv v use }
Just RecFun -> SCU { scu_calls = unitVarEnv v [(emptyVarEnv, [])] --
Added so we get specialisations even if function used in trivial way (i.e.
as a variable)
, scu_occs = emptyVarEnv }
Nothing -> nullUsage
}}}
Otherwise the pattern guard on (lookupVarEnv bind_calls fn) in specialise
fails, so we don't even get to call callsToPats.
I think this is the right change, because it should also mean that we get
call pattern specialisations for locally-bound functions that are e.g.
stored inside a data structure.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4945#comment:3>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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