ghc documentation doesn't explain difference between dwarf levels 1 2 and 3
I tried digging into current ghc source (well a 8.6.2 checkout) to track down where / how
debugLevel crops up.
The docs/examples support g0 (off ) through g3. But when looking at where debugLevel appears in code, there isn't any different currently at the GHC layer for g3 vs g2! (is there a difference at the C compiler layer?)