Nope, there's a lot of optimisations taking place on the core-to-core
phase, to ensure the core that gets unfolded into your .hi files is as
nice as possible. And then still there's things that actually stay as
calls into your compiled library -- for those, you'll want direct jumps
and so forth, which you get with -fvia-C -optc-O2 and above.

See my recent post on micro optimisations.

-- Don