Re: [PATCH] Prevent TYPE_PRECISION on VECTOR_TYPEs

[Richard Biener <rguenther@suse.de>]

On Wed, 28 Jun 2023, Jeff Law wrote:

> 
> 
> On 6/28/23 22:04, Li, Pan2 wrote:
> > It seems this patch may result in many test ICE failures on RISC-V backend.
> > Could you help to double confirm about it follow the possible reproduce
> > steps like blow? Thank you!
> I've one ICE due to this change as well but it wasn't in the
> tree-ssa-math-opts.code like this one is.  In my case we're in a place where
> it doesn't look like we expect a vector type to show up, but it does and we
> can likely just prune it away.
> 
> Anyway, your fault is in here:
> 
> 
> 
> divmod_candidate_p:
> 
>      if (TYPE_PRECISION (type) <= HOST_BITS_PER_WIDE_INT
>           && TYPE_PRECISION (type) <= BITS_PER_WORD)
>         return false;
> 
> TYPE is almost certainly a vector type.  The question we need to answer (and
> I'm not likely to get to it tomorrow) would be whether or not TYPE can
> legitimately be a vector type here.

I think GCN people wanted to make this code work for vectors, the
most obvious local fix is to use element_precision (type) above.

Note usually vector integer divisions are not a thing so this might
explain why you're seeing this only with RVV?

Richard.