[Mono-list] RE: Compilers emitting parsetrees - GCC's internal tree representation is unwieldy, but it's also quite
powerful. See: http://www.ncsa.uiuc.edu/~wendling/tree.html for a great
introduction to the structures involved. The back-end technically runs
in the same process as the front-end, but it does simply walk this tree
and emit code.
If you're looking for a human-readable form of this tree, try:
http://sourceforge.net/projects/introspector/.