[llvm-dev] enabling interleaved access loop vectorization

[Renato Golin via llvm-dev]

On 6 August 2016 at 00:18, Michael Kuperstein <mkuper at google.com> wrote:
> I agree that we can get *more* improvement with better cost modeling, but
> I'd expect to be able to get *some* improvement the way things are right
> now.

Elena said she saw "some" improvements. :)


> That's why I'm curious about where we saw regressions - I'm wondering
> whether there's really a significant cost modeling issue I'm missing, or
> it's something that's easy to fix so that we can make forward progress,
> while Ashutosh is working on the longer-term solution.

Sounds like a task to try a few patterns and fiddle with the cost model.

Arnold did a lot of those during the first months of the vectorizer,
so it might be just a matter of finding the right heuristics, at least
for the low hanging fruits.

Of course, that'd also involve benchmarking everything else, to make
sure the new heuristics doesn't introduce regressions on
non-interleaved vectorisation.

cheers,
--renato