ia64 vector mode support

["Jan Beulich" <JBeulich at novell dot com>]

Richard,

while I was about to get started with an attempt to implement these, I
got the notification that you just yesterday checked in some code going
into that same direction. Andrew comment in a bugzilla entry I had
opened a while ago for that pointed out that this is only for
autovectorization support, my intention was to get the intrinsics the
Intel compiler supports in a usable shape.
Now, the first and obvious question is: Are you intending to continue
your work into that direction? If so, I would probably want to stay away
from doing the same thing a second time.

What seems more problematic to me in this same area, however, is that
there appear to be more fundamental problems, at least with floating
point vector modes:
- Comparing with 3.4.3, the way they get passed as arguments or
returned has changed, mainly (as far as I can tell) because of changes
in common code. Is this intentional? If not, did anyone even notice?
- Regardless of whether I look at the old scheme or the new one, I am
fairly convinced that the parameter/return value passing is wrong. My
main problem here is to determine how to correct it: Matching the ABI
(according to which, as I'm reading it, these should be treated as
HFAs), matching the Intel compiler (which I can compare with), or
matching some other compilers (which I have no access to) that may use
yet different mechanisms.

Jan