vectorizing optimization

[Andrea 'Fyre Wyzard' Bocci]

Hi everybody.
It's been some times now, I've got this recurrent idea:
Implementing an automatic vectorizing optimization pass would (if it 
worked) A Good Thing.
And, from my this-is-the-first-time-I-look-at-something-as-complex-as-gcc 
point of view, quite hard to do.
Anyway, as I hope to have much spare time by a week (I'm graduating at the 
beginning of December), I'd like spend some of it learning the gcc intenals 
and trying to implement it.
Now, my questions:
1) I've seen that vector instructions support is being added to the 3.1 
branch. Is anybody already working on a vectorizing pass?
2) At what level it would be better implemented ? tree or RTL ? In a branch 
from the main tree, or in conjunction withe the AST branch ?
3) In a machine independent fashion, or for a specific architecture (eg., 
386) ?

Thanks in advance for your info - and keep on with the good work, it IS 
much appreciated :-)
fwyzard