On Mon, Jul 31, 2023 at 11:40 AM Richard Biener <rguenther@suse.de> wrote:
>
> On Sun, 30 Jul 2023, Uros Bizjak wrote:
>
> > Also introduce -m[no-]mmxfp-with-sse option to disable trapping V2SF
> > named patterns in order to avoid generation of partial vector V4SFmode
> > trapping instructions.
> >
> > The new option is enabled by default, because even with sanitization,
> > a small but consistent speed up of 2 to 3% with Polyhedron capacita
> > benchmark can be achieved vs. scalar code.
> >
> > Using -fno-trapping-math improves Polyhedron capacita runtime 8 to 9%
> > vs. scalar code.  This is what clang does by default, as it defaults
> > to -fno-trapping-math.
>
> I like the new option, note you lack invoke.texi documentation where
> I'd also elaborate a bit on the interaction with -fno-trapping-math
> and the possible performance impact then NaNs or denormals leak
> into the upper halves and cross-reference -mdaz-ftz.

The attached doc patch is invoke.texi entry for -mmmxfp-with-sse
option. It is written in a way to also cover half-float vectors. WDYT?

Uros.