programmable GCC?

[Russell Potter]

Just wondering: could someone tell me
whether any useful subsets of GCC's
functionality, such as its conversion
from intermediate code to the assembly
language of one of GCC's vast array
of output architectures, or its
advanced code optimisation capabilities,
have been separated into an independent
library/ies that will, when called,
allow calling code to then leverage
this existing functionality?

I realise projects such as "libjit"
attempt to accomplish some of this,
but they're really just duplicating
GCC's work in doing so, aren't they?
seems like wasted effort to me ... :-)

Russell