[Haskell-cafe] Identifying thunks from GHC heap profiles

I am trying to debug a stack overflow that seems to be caused by a large chain of thunks being evaluated all at once. I have some profiles generated using +RTS -hd -RTS that show some promising candidates, but they have generated names like Module.sat_s9et, Module.sat_s9jk, etc Is there any convenient way to map these generated names back to something recognizable in the source? I tried using +RTS -hc -hdsat_s9et -RTS to filter SCCs as suggested in http://hackage.haskell.org/trac/ghc/ticket/1639, but the resulting profile is always empty. I also tried to use -fext-core and -ddump-simpl to dump some intermediate representations but none of the thunk names seem to appear in those outputs.