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Re: [tree-ssa] Re: auto vectorization in gcc



On Wednesday, July 23, 2003, at 12:50 PM, Dorit Naishlos wrote:



This is very much along the same lines as I was envisaging.  Given we
currently have some time and resources that could be used on a project
like this would you be interested / able tocolaborate on this project?

Sure! (there's a lot to be done...)


We're still at the design phase - trying to decide which
vectorization scheme we want to implement, what is the minimal
essential infrastructure required in order to vectorize even
the simplest loop/code-sequence, and how much of this infrastructure
is already available, or is being developed and will be available (and
when).

I understand that Sebastian Pop is working on IV detection,
and that data dependence analysis will be based on that infrastructure.
Where does that stand? Sebastian, were you planning to work on the
dependence graph too?

The project's web page states that loop normalization
and loop canonicalization are on the todo list. Is someone working
on that? (Daniel Berlin?)

Is it actually necessary? A lot of papers i've read recently think it isn't.


I guess that's pending the IV detection work too?


No, it normalized trivial ivs.


You can easily detect trivial iv's in tree-ssa form.

They have a single arity 2 phi node in the first block of the loop, with one edge/value coming from a def in the pre-header of that loop, and one edge/value coming from the latch block of that loop.


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