On Fri, Mar 22, 2019 at 10:35:45AM +0100, Uros Bizjak wrote:
> On Fri, Mar 22, 2019 at 9:41 AM Jakub Jelinek <ja...@redhat.com> wrote:
> > The following patch adds forgotten avx512f fma instrinsics for masked scalar
> > operations.
> >
> > Bootstrapped/regtested on x86_64-linux and i686-linux (on skylake-avx512),
> > ok for trunk?
>
> There are several possibilities to mark the 1st and the 2nd operand of
> fma pattern as commutative ("%"). However, there are already existing
> patterns without commutative operand, so this improvement could be
> eventually submitted as a follow-on patch.
I actually don't know where it would be safe to use % in these masked
patterns, except perhaps avx512f_vmfm{add,sub}_<mode>_mask3<round_name>.
For FMA, naturally only the two operands that are multiplied should be
commutative, but in most patterns one of those two uses "0" or "0,0"
constraint and there is one or two match_dup 1 for it, so it really
isn't commutative.
Which leaves us with the 4 mask3 patterns only, as I said above, for
the first two where neither of those are negated I think % should be ok.
For the .*fnm{add,sub}.*mask3.* ones I'm not sure, because one of them
is negated. On the other side, seems various other existing fnm*
patterns use % even on those.
Jakub
