- No Optimisation
ghc -ddump-simpl -ddump-to-file -dsuppress-uniques -dsuppress-coercions -dsuppress-type-applications -dsuppress-unfoldings -dsuppress-idinfo -fforce-recomp forDdumpComp.hs
./forDdumpComp +RTS -s
ghc -ddump-simpl -ddump-to-file -dsuppress-uniques -dsuppress-coercions -dsuppress-type-applications -dsuppress-unfoldings -dsuppress-idinfo -fforce-recomp forDdumpCompNew.hs
./forDdumpCompNew +RTS -s
Both perform badly
You can look at the .dump-simpl files and they are different.
- -O1 and -O2
ghc -O1 -ddump-simpl -ddump-to-file -dsuppress-uniques -dsuppress-coercions -dsuppress-type-applications -dsuppress-unfoldings -dsuppress-idinfo -fforce-recomp forDdumpComp.hs
./forDdumpComp +RTS -s
ghc -O1 -ddump-simpl -ddump-to-file -dsuppress-uniques -dsuppress-coercions -dsuppress-type-applications -dsuppress-unfoldings -dsuppress-idinfo -fforce-recomp forDdumpCompNew.hs
./forDdumpCompNew +RTS -s
Now both perform better but the specialised version is about x5 faster!