auto vectorization in gcc

[law@redhat.com]

In message <Pine.LNX.4.44.0307172000580.10372-100000@wotan.suse.de>, Michael Ma
tz writes:
 >Hi,
 >
 >On Thu, 17 Jul 2003, Richard Henderson wrote:
 >
 >> The tree level is *more* capable than the rtl level at representing
 >> vector types (and thus operations).  I think all we need is some small
 >> amount of info from the target about vector widths and memory blocking,
 >> and then the transformation should happen at the tree level.
 >
 >I agree.  Autovectorization should be much easier on tree level.  The
 >required transformations are complicated enough as is, without having to
 >deal with RTL issues.
What I've always envisioned is that we'd do the vectorization at the tree
level, building vectors as wide as possible (up to some limit).  Then
at the tree->rtl phase we'd break the vectors down to whatever size the
target actually supports.  The basic idea being to not have a lot of
target dependencies in the vectorizer.

jeff