[PATCH] D89031: [SVE] Add support to vectorize_width loop pragma for scalable vectors

[Sjoerd Meijer via Phabricator via cfe-commits]

SjoerdMeijer added a comment.

Thanks @david-arm for posting this proposal to the cfe list.
My confusion has been cleared up. The (new) proposal is to have:

1. vectorize_width(X) where X is an integer.
2. vectorize_width(X, fixed|scalable)
3. vectorize_width(fixed|scalable)

And with that 3rd option I agree that this allows us to express everything we want, and this patch needs adapting to this new proposal (just stating the obvious for clarity/completeness)

If scalable is used on a target that doesn't support this, a warning and falling back to fixed seems like the right thing to do.

I did have concerns about this, similarly like @fhahn:

> Hm, I am just a bit worried that it might be a bit confusing to users that do not know what scalable vectors are (it is obvious when knowing all about SVE, but I would assume most people don't necessarily know what this means). I guess that is not the biggest deal, as long vectorize_width(X, scalable) works for every target.

But since the new scalable option is opt-in, people don't need know about this if they don't want/need to, this should (hopefully) not be the case.


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  https://reviews.llvm.org/D89031/new/

https://reviews.llvm.org/D89031