On 30/08/2023 14:01, Richard Biener wrote:
On Wed, Aug 30, 2023 at 11:15 AM Andre Vieira (lists) via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
This patch adds a machine_mode parameter to the TARGET_SIMD_CLONE_USABLE
hook to enable rejecting SVE modes when the target architecture does not
support SVE.
How does the graph node of the SIMD clone lack this information? That is, it
should have information on the types (and thus modes) for all formal arguments
and return values already, no? At least the target would know how to
instantiate
it if it's not readily available at the point of use.
Yes it does, but that's the modes the simd clone itself uses, it does
not know what vector_mode we are currently vectorizing for. Which is
exactly why we need the vinfo's vector_mode to make sure the simd clone
and its types are compatible with the vector mode.
In practice, to make sure that a SVE simd clones are only used in loops
being vectorized for SVE modes. Having said that... I just realized that
the simdlen check already takes care of that currently...
by simdlen check I mean the one that writes off simdclones that match:
if (!constant_multiple_p (vf, n->simdclone->simdlen, &num_calls)
However, when using -msve-vector-bits this will become an issue, as the
VF will be constant and we will match NEON simdclones. This requires
some further attention though given that we now also reject the use of
SVE simdclones when using -msve-vector-bits, and I'm not entirely sure
we should...
I'm going on holidays for 2 weeks now though, so I'll have a look at
that scenario when I get back. Same with other feedback, didn't expect
feedback this quickly ;) Thank you!!
Kind regards,
Andre
