Never mind, I figured it out. It is the CoreTidy pass of the compilation pipeline: https://ghc.haskell.org/trac/ghc/wiki/Commentary/Compiler/HscMain Cheers, Gabor On 5/29/18, Gabor Greif wrote:

Hi devs,

I have a simple question, but could not find an answer yet. The same variable (I checked!) appears in two dumps with different names and different external visibilities. Which pass transforms this variable to a global id, and why? Shouldn't a LclId remain local along the entire optimisation chain?

Any hint appreciated!

Cheers and thanks,

Gabor

Snippets from dumps below

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-rw-r--r-- 1 ggreif sw12 3281225 May 29 14:14 TcSMonad.dump-stranal

-- RHS size: {terms: 2, types: 1, coercions: 0, joins: 0/0} lvl_sOra :: TcTyVarDetails [LclId, Unf=Unf{Src=<vanilla>, TopLvl=True, Value=False, ConLike=False, WorkFree=False, Expandable=False, Guidance=IF_ARGS [] 20 0}] lvl_sOra = ghc-prim-0.5.3:GHC.Magic.noinline @ TcTyVarDetails vanillaSkolemTv

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-rw-r--r-- 1 ggreif sw12 1438015 May 29 14:14 TcSMonad.dump-simpl

-- RHS size: {terms: 2, types: 1, coercions: 0, joins: 0/0} TcSMonad.isFilledMetaTyVar_maybe2 :: TcTyVarDetails [GblId, Unf=Unf{Src=<vanilla>, TopLvl=True, Value=False, ConLike=False, WorkFree=False, Expandable=False, Guidance=IF_ARGS [] 20 0}] TcSMonad.isFilledMetaTyVar_maybe2 = ghc-prim-0.5.3:GHC.Magic.noinline @ TcTyVarDetails vanillaSkolemTv

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