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Re: [patch] Make jump threading preserve loops

On Wed, 2006-11-08 at 14:41 +0200, Dorit Nuzman wrote:

> Two options to consider (beyond really calling vect_analyze_loop):
> - don't peel if -ftree-vectorize is on
Probably overkill.

> - maybe just check dependences in the loop, as a measure to evaluate
> vectorizability. it's an anlysis that is useful to have as a stand-alone
> anyhow (and mostly already is - compute_data_dependences_for_loop I guess).\
This is roughly what I was suggesting -- apply a set of simple tests
which can (cheaply) determine if a loop might be vectorizable -- erring
on the side of assuming the loop might be vectorizable.

I wouldn't be terribly surprised to find that there's a few tests we
can apply which would allow us to identify a significant portion of
the unvectorizable loops.


> this would still spoil the alignment, which is *very* unfortunate. People
> put a lot of attention to structuring their code such that the data would
> be aligned for vectorization (just two recent examples:
> I think we should
> strongly consider Jeff's comment above.
Good point.  


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