Re: [PATCH 10/25] Convert BImode vectors.

[Andrew Stubbs <andrew_stubbs at mentor dot com>]

On 05/09/18 13:05, Richard Biener wrote:
> On Wed, Sep 5, 2018 at 1:51 PM <ams@codesourcery.com> wrote:
> > GCN uses V64BImode to represent vector masks in the middle-end, and DImode
> > bit-masks to represent them in the back-end.  These must be converted at expand
> > time and the most convenient way is to simply use a SUBREG.
>
> x86 with AVX512 uses SImode in the middle-end as well via the get_mask_mode
> vectorization target hook.  Maybe you can avoid another special-case
> by piggy-backing on
> that?

That's exactly what I wanted to do, but I found that returning 
non-vector modes ran into trouble further down the road.  I don't recall 
the exact details now, but there were assertion failures and failures to 
vectorize.

That was in a GCC 8 codebase though, so is the AVX thing a recent change?

Andrew