Re: Enabling vectorization at -O2 for x86 generic, core and zen tuning

[Segher Boessenkool <segher at kernel dot crashing dot org>]

On Mon, Jan 07, 2019 at 09:29:09AM +0100, Richard Biener wrote:
> On Sun, 6 Jan 2019, Jan Hubicka wrote:
> > Even though it is late in release cycle I wonder if we can do that for
> > GCC 9?  Performance of vectorization is very architecture specific, I
> > would propose enabling vectorization for Zen, core based chips and
> > generic in x86-64. I can also run benchmarks on buldozer. I can then
> > tune down the cheap model to avoid some of more expensive
> > transformations.
> 
> I'd rather not do this now, it's _way_ too late (also considering
> you are again doing inliner tuning so late).

This probably should be more generic than just x86 really, we have similar
problems on Power (-O3 is almost always faster than -O2, which is bad).
Likely other archs have the same problems.

But yes, too late for GCC 9.


Segher